This week Sports on Earth presents a four-part series on the Running Back. On Tuesday, Matt Brown covered Baylor, which has the deepest group of running backs in college football. Today, Mike Tanier breaks down the best running back rivalries in NFL history.

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Tom Brady versus Peyton Manning is the greatest quarterback rivalry in football history, and we can all name the runners up: Starr versus Unitas, Bradshaw versus Staubach, Aikman versus Young, Marino versus Kelly, and so on.

Since we can all name the best quarterback rivalries, and we all know which one is best, there is not much point to an article about them, is there?

Running back rivalries are a different story. Some of the greatest rushers in NFL history - many of whom were more important to their teams than their quarterbacks -- competed head-to-head for Super Bowls, rushing titles, or simple bragging rights. While you hang your Manning stockings under the Brady tree this week, take a moment to remember these legendary rivalries of yesteryear.

5. Edgerrin James versus Ricky Williams

Ricky Williams was the talk of the 1999 draft class. He rushed for 2,327 yards and 29 touchdowns en route to a Heisman trophy in his senior season. Eagles fans wanted Williams so badly that they threatened to boo any other player selected, and they did. Mike Ditka, then the Saints head coach, threatened to trade all of his draft picks to acquire Williams, and he did. In a draft class loaded with quarterback prospects, Williams was the true superstar.

Yet Williams was not even the first running back drafted that year. The Colts chose Edgerrin James with the fourth pick overall. Williams went to the Saints fifth. The pair immediately became linked in the football consciousness.

Colts GM Bill Polian understood at the time what Ditka and armchair draftniks were just figuring out: power runners like Williams are often poor fits in modern offenses. James was smaller, quicker, and much more useful as a receiver: the perfect complement to Peyton Manning. Plus, Williams was an odd duck. His anxiety disorders were not yet diagnosed, but a soft-spoken, philosophical, somewhat-mystical running back was as alien to the 1999 NFL as a running back in a wedding dress. NFL locker rooms were ready for the street-toughened James, but not the shy, moody Williams.

James was also more NFL ready than Williams, rushing for over 3,000 yards, catching 125 passes, and scoring 35 touchdowns in his first two seasons. Williams struggled to crack 1,000 yards while getting force-fed the football in Ditka's out-of-date system. He suffered injuries. His eccentric behavior came under scrutiny. The Saints soured on him, but the Dolphins were ready to trade four draft picks to give Williams a second chance. A transfer to the AFC meant that Williams and James would finally face off on the field in September of 2002.

The contrast between James and Williams, on the field and off, made for an easy pregame storyline. James refused to talk about Williams or any "rivalry," making it clear that he did not feel Williams was in his class. "And he's right," Williams told Dan Le Batard in the Miami Herald. "I'm not in his league. I definitely agree with him. I'm not being modest. It's the truth. He's a better running back. Look at his numbers. I've been getting a lot of respect, too much, because of what I did in college. Edgerrin is the No. 1 back in the league.''

Williams may not have been in James' league, but he was in a better offense than the one that ground him up in New Orleans. James, meanwhile, was on the mend from an ACL tear. James showed no ill effects from the injury in their first meeting, rushing for 138 yards and catching eight passes, but Peyton Manning had a three-interception game. Williams answered with 132 rushing yards, 62 receiving yards, and one touchdown in a 21-13 Dolphins victory.

Williams came away with a win and held his own on the stat sheet, but he only had praise for Edge. "It was fun watching him," Williams said after the game. "He can run, can cut, he can stop on a dime. He can hit the seams, and he can run."

Williams went on to his greatest season in 2002, rushing for 1,853 yards and 16 touchdowns. James dealt with lingering ACL effects all year. When they met again in 2003, the Colts were 6-1, the Dolphins 5-3, and the easy boom-versus-bust storyline was muddied by Williams emergence and Edge's injuries. James won the rematch, rushing 26 times for 89 yards and a touchdown in a 23-17 Colts win. Williams rushed just 13 times for 36 yards. "The way the game was going, we didn't have a chance to run the ball as much as we wanted," Williams said after the game.

The Williams-James rivalry never turned out to be as good as it could have been. Williams' career became a patchwork of marijuana suspensions and on-and-off retirements after the 2003 season. James enjoyed a pair of excellent seasons in 2004 and 2005, but the Colts let him leave via free agency. Separated from Manning and not as elusive as he was in 1999-2000, James became for the Cardinals what Williams was for the Saints: a plodder getting force-fed the football in a second-rate offense.

When the pair met in September of 2008, there were no 1999 draft retrospectives or compare-and-contrast articles about the aging rushers. James rushed for 55 yards, Williams just 28 in a 31-10 Dolphins victory. No one knew at the time that Williams and the Dolphins would soon introduce the NFL to the Wildcat offense, while James and the Cardinals would shrug off an awful early season and engineer an unlikely Super Bowl run.

Williams and James did not meet often, but they remain together in our memories: a study in contrasts, a cautionary tale about getting too enamored of a prospect, and a reminder that stud-versus-bust narratives are rarely all that cut and dry.

4. Earl Campbell versus Franco Harris

The Steelers' primary rivals during the Steel Curtain era were the Cowboys, their regular Super Bowl opponent, and the Raiders, their perennial AFC challengers. But a new foe emerged in 1978 when a bruising rookie running back named Earl Campbell joined an Oilers team that already had a nasty defense. Campbell announced his NFL arrival with three touchdowns in a 24-17 Monday night victory over the Steelers, who entered the game with a 7-0 record. "Maybe we were feeling that we couldn't be beat," Steelers linebacker Jack Lambert said after that game. "Now, we know we can."

Campbell gave the Steelers a feeling that they could be beat, but the Oilers did not beat the Steelers all that often. The Steelers had their own great running back in Franco Harris, and Steelers-Oilers games became grueling infantry battles. Campbell plowed into the trenches against Jack Lambert and the Steel Curtain, then Harris and Rocky Bleier took turns against Curley Culp, Gregg Bingham, and the rest of Bum Phillips' Oilers defense. When the Steelers met the Oilers again in December of 1978, quarterbacks Terry Bradshaw and Dan Pastorini threw for just 97 and 94 yards. Harris and Bleier combined for 168 rushing yards, a beat-up Campbell gained just 41, and the Steelers prevailed 13-3.

But Campbell made the Oilers a playoff team, and he carried them through two postseason victories (53 carries, 202 yards, 2 TDs) to face the Steelers in the AFC Championship game. "Next week will be a bigger thrill than winning the Heisman, if everything goes right," Campbell said before the game.

Everything went wrong. Icy, sloppy January conditions favored the Steelers against the dome-based Oilers. Campbell tried to run off tackle on the game's opening play but got dumped by Jack Ham for a two-yard loss. "The tone was set," Joe Greene said of the hit. Franco Harris scored a seven-yard touchdown in the first quarter. "That's all we need," Steelers defender L.C. Greenwood said to a teammate on the sideline. Greenwood was right: the Steelers won 35-5.

Harris rushed for 51 yards, with Bleier contributing 45. Campbell finished with 62 yards on 22 carries as the Oilers turned the ball over nine times. "Their whole game was to run Campbell and go to play-action passes when they thought the running game was slowing down," Ham said. "They just couldn't get it done today."

Campbell brought the Oilers back to the playoffs to face the Steelers one year later, with the help of a 33-carry, 109-yard effort in a 20-17 December victory in the Astrodome that knotted the teams at 11-4 and threw a scare into the Steelers. But despite taking an early lead on an interception return touchdown, the Oilers could not get Campbell going. He finished the game with just 15 yards on 17 carries as the Steelers slowly pulled away for a 27-13 win. "Earl likes to cut back a lot," Greenwood said after the game "But instead of gambling the way we did the last time we played Houston, we jumped in the holes and didn't give him any daylight." Harris rushed for 85 yards and caught six passes for 50 yards in the victory.

Campbell finally earned a measure of revenge in a Thursday night game in 1980. He rushed for 81 yards in a 6-0 victory that knocked the Steelers out of the playoffs and, in many ways, signaled the end of the Steel Curtain era. But the Oilers would lose to the Raiders in the playoffs, and the carries took their toll on Campbell after his 1,934 yard heroics of 1980. Unlike Harris, he never had a true complementary back like Bleier, and he never had a quarterback like Bradshaw. The Steelers won both playoff matchups, which led to two Super Bowls. The Oilers settled for the lovable spoiler role.

Harris remembers just how special his rival was. When asked by the New York Times a few years ago who the best running back of his era was, Harris selected Walter Payton. "But if you're looking at different styles, no one was a tougher runner than Earl Campbell," Harris said. "Oh my God, that guy could run."

3. Jim Brown versus Jim Taylor

Jim Brown was arguably the greatest player in NFL history. Jim Taylor may have been the greatest running back ever to be the second-best running back of his generation.

From 1960 through 1964, Brown and Taylor finished first and second in the NFL in rushing, in that order, four times. Taylor took advantage of Brown's off year in 1962 to claim his only rushing title, gaining 1,474 yards, scoring 19 touchdowns, and earning MVP honors. Brown won most of the rushing titles, but Taylor had a heck of a consolation prize: as a member of the Vince Lombardi Packers, he won four NFL titles, including Super Bowl I.

Taylor-versus-Brown comparisons were almost as common in the early 1960s as Brady-Manning comparisons are today. Brown, bigger yet more elusive, could burst through tacklers or go around them. Taylor, built like a small tank, was elusive when he wanted to be -- but rarely wanted to be. "It takes a lot of guys to bring down Taylor and Brown," Hall of Fame linebacker Chuck Bednarik once said. "But Brown knows when it is no use to keep driving. Taylor doesn't."

Vince Lombardi gave a similar scouting report: "Jim Brown will give you that leg and then take it away from you. Jim Taylor will give it to you and then ram it through your chest!"

The first meeting between Brown and Taylor in 1961 was billed as a both an NFL Championship preview and a head-to-head clash between the NFL's two best running backs. Taylor ended up dominating the matchup with 158 yards and four rushing touchdowns in a 49-17 Packers romp. Brown rushed for just 72 yards. "It was satisfying to have a game like this on the same field with Brown," Taylor said afterwards. "We all knew that this game would tell how good we really were."

No one would question the Lombardi Packers again after they won NFL Championships in 1961 and 1962. But 1964 was an off year for the Packers, who were 5-5 when they faced a Browns team riding high at 8-1-1. Brown rushed for 74 yards and one touchdown, while Taylor rushed for 63 yards but two touchdowns. Taylor's second touchdown gave the Packers a 28-14 lead, and they held on to win 28-21. Brown won both the rushing title and the NFL Championship that year; Taylor had to settle for a head-to-head victory.

Brown and Taylor finally met in a championship game after the 1965 season (they also met once in one of those awful 1960s Playoff Bowls, but no one cares). Three inches of snow fell before kickoff, and though the field was covered with tarp, rain and sleet during the game turned Lambeau Field into a mud pit. The Packers and Browns traded touchdowns early, but while Jim Brown versus Jim Taylor may have been a showdown for the ages, Bart Starr versus Frank Ryan was not. Ryan, a pretty good quarterback but no match for the Lombardi Packers, threw two interceptions as the game slowly slipped away from the Browns. Jim Brown earned fewer and fewer carries as the Browns reverted to catch-up mode. An 11-play, 90-yard Packers drive in the third quarter, with Taylor and Paul Hornung trading carries, made the score 20-12 while keeping Brown off the field. The Packers won 23-12. Brown finished with 50 yards, Taylor 95, Hornung 106.

That's how the Brown-Taylor rivalry went: Brown won awards, Taylor won championships with the help of the best coach and teammates anyone in professional sports could hope for. Each found his niche, both reached the Hall of Fame, and fans of the era knew they were witnessing a unique rivalry between two all-time greats. "First or second, second or first, the league has never had two such great fullbacks at one at the same time," wrote columnist Oliver E. Kuechle of the Milwaukee Journal in 1964, whose loyalties may have leaned a bit toward the Packers. "…And certainly in Taylor, the smaller and slower, none who has always given so much of himself, and who if he doesn't catch Brown again as in 1962 will surely be right at his heels."

2. Emmitt Smith versus Barry Sanders and Thurman Thomas

How do you like your running backs? Chopping at the heart of a defense like a hatchet, five yards at a time? Pirouetting in the backfield to mix three-yard losses with 60 yard scampers? Or running, catching, and blocking like a vital circuit in a state-of-the-art machine?

In the 1990s, you did not have to choose. Emmitt Smith pummeled opponents into submission as the power train for the greatest team of his era. His rival for rushing titles was Barry Sanders, whose real-life spins and jukes look computer generated to modern eyes. His rival in the Super Bowl was Thurman Thomas, precision-tuned component of a cutting-edge offense. Emmitt prevailed on both fronts, but he needed a lot of years and some help from his friends to do it.

History tells us that Smith's Cowboys won three Super Bowls while Sanders' Lions tinkered with their gadget offense year after year, barely making the playoffs at the last moment to save their coach's job. So it may come as a shock to learn that the Lions were 3-1 against the Cowboys in head-to-head Smith-Sanders showdowns, including one playoff blowout.

Fans knew they were watching two special running backs when Smith and Sanders first squared off in 1991. Smith and Sanders knew it too. "He's in a class by himself," Smith said before that first meeting. "I'm excited to get to see him play up close for 60 minutes." Sanders was also impressed by his opponent: "He may not use as many moves as I do, but he finds a way to avoid tacklers, and that's the bottom line. He's got his own style, like all great runners." Neither player put on much of a show in the Lions' 34-10 rout, however: Sanders gained just 54 yards on 21 carries with a short touchdown catch, Smith 64 yards on 16 carries.

The Cowboys and Lions met again in the 1991 playoffs. The running back showdown was on everyone's mind, except Smith's and Sanders'. "I know people like to see individual players go against each other," Sanders said before the game. "But we have a tremendous opportunity with the Lions. That's what's on my mind." The Lions made the most of that opportunity. The Cowboys defense, not quite Super Bowl caliber yet, had trouble with Wayne Fontes' run-'n'-shoot system and overcompensated to stop Sanders. Lions quarterback Erik Kramer threw three touchdowns in a 38-6 laugher. Newspapers solemnly noted after the game that Smith won the rushing yardage battle, 80 to 69 (though Sanders had more total yards).

No one would laugh at the Cowboys for a long time after that. But in 1991, neither Smith nor Sanders was the NFL's best running back. That honor belonged to Thurman Thomas, Sanders' college teammate, who earned league MVP honors while gaining 2,038 yards from scrimmage while leading the Bills to the Super Bowl. Smith and Sanders were destined to trade the rushing title back and forth for a decade -- each led the league four times -- but Smith and Thomas were destined to meet in the Super Bowl.

Thurman Thomas had a reputation as a top playoff competitor early in his career. He would have been MVP of Super Bowl XXV for his 190-total yard, one-touchdown effort if Scott Norwood's field goal attempt had sailed true. Two Super Bowls later, Thomas started well against the Cowboys, scoring a touchdown after Steve Tasker blocked a punt. But Thomas fumbled at the Buffalo 20-yard line before halftime, allowing the Cowboys to score 14 quick points to take a 28-10 lead. Smith spent the second half grinding out 108 yards to protect a lead that would swell to 52-17. Thomas finished with just 19 yards on 11 carries.

Somehow, things got even worse for Thomas when the Cowboys and Bills met again in the next Super Bowl. Thomas fumbled after a first-quarter catch to set up a Cowboys field goal. He scored a touchdown to help the Bills build a 13-6 lead, then made a disastrous mistake to start the third quarter. Defender Leon Lett stripped the ball from Thomas, James Washington scooped and scored, and that snake-bit feeling set in again for the Bills. "To me, that was the big play of the game," a solemn Thomas said afterward. "It really turned the game around."

Emmitt Smith did what he did best once the Cowboys had the lead: he dropped an anvil on his opponent's chest. The next Cowboys drive consisted of seven Smith runs for 61 yards and a touchdown, with one three-yard pass wedged in. Smith would finish with 30 carries, 132 yards, and two touchdowns in a 30-13 win.

Ever gracious, Smith hugged Thomas after the game and introduced the Bills running back to his niece. "I want you to meet the best running back in the National Football League," Smith said. "I told him, 'don't even try that with me,'" Thomas later said. "We both know you're the best -- you proved it today."

Smith bested Thomas in two Super Bowls, and he eventually passed Sanders and everyone else in rushing yards and rushing touchdowns. He was the best running back of his generation, but he now copes with some revisionist history. Smith played with Hall of Fame teammates behind the best offensive line of his era. He hung around long past his prime, ending his career as a plodder for the Cardinals who looked nothing like the Super Bowl-era superstar. Twenty years later, Sanders' highlights still dazzle; Cowboys highlights show a running back running untouched off tackle behind a caravan of blockers. Search the blogosphere, and it's not hard to read that Sanders was the true superstar, while Smith was some "product of the system."

That's not how it was. "A great back like Emmitt Smith is very smooth and flowing," Lions safety William White said in 1992. "It doesn't look like he's running hard, but he makes excellent use of his blockers. Barry will embarrass you in front of your wife and kids and family; he'll hand you your jockstrap on national TV."  

A great back like Thurman Thomas, meanwhile, can change offensive strategy forever. Smith's I-formation gut-punches won Super Bowls and Barry Sanders' run 'n' shoot jukes broke records and ankles, but Thomas taught running backs how to thrive in an up-tempo offense filled with shotgun formations, short passes, and delayed handoffs. Today's running backs owe a greater debt to Thomas than to Smith or Sanders. That's a greater legacy for a truly great runner than a bunch of Super Bowl fumbles.

1. Bronko Nagurski versus Clarke Hinkle

Go back far enough and running back rivalries become true head-to-head matchups. Running backs in the old days doubled as linebackers, which means they got to square off and see who could tackle whom. Imagine Adrian Peterson and Marshawn Lynch colliding in a hole and you get a sense of just how intense the game was in the leather-helmet 1930s.

Bronko Nagurski and Clarke Hinkle were the Peterson and Lynch of the 1930s. They were also the Patrick Willis and Lance Briggs, and Hinkle was Andy Lee and David Akers in his free time. Nagurski, a 230-pound Bears fullback in an age of 220-pound linemen, was the most feared runner and tackler of his era. Hinkle, much smaller but just as tough and totally fearless, was a jack-of-all-trades who played fullback, linebacker, kicker punter, and whatever else Curly Lambeau asked of him for the Packers.

When Nagurski first faced Hinkle in 1932, he was eager to learn what the highly-touted rookie was capable of. Nagurski demanded a handoff in the huddle and told his teammates not to block Hinkle. "I want a piece of his ass," Nagurski said, according to legend. Hinkle met Nagurski in the hole and got steamrolled. He needed smelling salts and four stitches to his face on the sideline. "He darn near killed me," Hinkle later said.

Hinkle paid Nagurski back in 1935. He raced toward the sideline on a run-punt option play with Nagurski in pursuit, but instead of kicking or running out of bounds, he lowered his shoulder. The two future Hall of Famers collided head-to-head. Hinkle was knocked five yards backward, but Nagurski's nose was broken.

When the Packers traveled to Soldier Field a few weeks later, one of the Chicago newspapers ran a headline which read "Nagurski to Get Hinkle." Hinkle recalled that Nagurski "got" him with a hit up the middle so ferocious that it drove Hinkle straight into the backfield, but the hit was clean. "Nagurski wasn't out to get me, even though that's what some of the sportswriters thought," Hinkle said.

"I was able to tackle him and handle him pretty good," Hinkle said of Nagurski, "but I've got a lot of scars to show for it." Nagurski and George Halas initially accused Hinkle of dirty tactics, but the two toughest players in an era of toughness came to respect each other. The Packers and Bears were usually near the top of the standings of the ten-team NFL in those days, their games a decade-long procession of scoreless ties and 2-0, 7-6, and 6-2 final scores. Hinkle and Nagurski's rushing stats look like nothing today (Nagurski's 586 yards in 1934 were the most in a season by either player) but how many yards would Adrian Peterson gain in a 13-game season on muddy fields if he also had to play linebacker and punt?

Nagurski eventually presented Hinkle at his Pro Football Hall of Fame ceremony. "There was no animosity between the two of us," Hinkle said. "He was simply the most bruising back that I ever played against. I believe he felt the same way about me." The enemies who became friends were the greatest rival running backs ever, and will remain on top unless running backs start breaking each other's noses again.

Hinkle's quotes from "What a Game they Played: An Inside Look at the Golden Era of Pro Football," by Richard Whittingham.