The College Football Playoff semifinals are back where they belong in the fourth year of the system: New Year's Day. It's always been a holiday made for the biggest college football games, and this season's playoff delivers two enticing semifinals: Oklahoma vs. Georgia in the Rose Bowl and Clemson vs. Alabama in the Sugar Bowl. The winners will meet in Atlanta for the national championship on Monday, Jan. 8. Here's what to watch in the semifinals.

Rose Bowl

No. 2 Oklahoma vs. No. 3 Georgia

5 p.m. ET, ESPN
Announcers: Chris Fowler, Kirk Herbstreit, Tom Rinaldi and Maria Taylor

Matchup history: This is the first meeting between Oklahoma and Georgia. They've never crossed paths in a bowl game; they've never scheduled each other in a nonconference series. Despite the fact that neither team is in the Big Ten or Pac-12, they have, however, both made one trip to the Rose Bowl. Oklahoma's one Rose Bowl appearance was somewhat recent, as Ohio State's trip to the BCS title game at the Fiesta Bowl in 2002 left open a vacancy in Pasadena, which Oklahoma filled in a 34-14 win over Washington State. Georgia's Rose Bowl history dates way back to the 1942 season, with a team led by Heisman Trophy winner Frank Sinkwich. The Bulldogs were in the driver's seat for the national title deep into November before they were upset by Auburn, 27-13. They proceeded to beat No. 2 Georgia Tech to move back up to No. 2, and they ended the season by taking own UCLA, 9-0, in the Rose Bowl on a blocked punt for a safety and a Sinkwich touchdown, both in the fourth quarter.

How Oklahoma got here: The Sooners have earned their second playoff trip in three years -- they lost a semifinal to Clemson in 2015 -- behind the duo of first-year head coach Lincoln Riley and Heisman-winning quarterback Baker Mayfield, plus a superb offensive line. A home loss to Ohio State ultimately cost Oklahoma a playoff bid last year; this year, the Sooners made the return trip to Columbus and got revenge, beating the Buckeyes 31-16 in a game that helped send Oklahoma to the playoff and keep Ohio State home. The Sooners faltered in a stunning home loss to Iowa State, but they rallied, improved on defense over the course of the year and closed the regular season on an eight-game winning streak. That included an easy 41-17 win over TCU in the return of the Big 12 championship game. The Sooners have won three straight Big 12 championships, and now they'll pursue their first national title since 2000.

How Georgia got here: A sleeping giant has transformed itself into a budding powerhouse. Kirby Smart has proved to be a phenomenal recruiter since returning to his alma mater as head coach; after a mediocre 8-5 debut season on the field in 2016, Smart showed he can be a phenomenal program leader in general. Led by a veteran defense and a dominant running game, Georgia is 12-1, with true freshman Jake Fromm starting all but the opener at quarterback. The Bulldogs won Fromm's first start at Notre Dame by a point and crushed just about everyone else on their schedule beyond a Nov. 11 loss at Auburn. Three weeks after that defeat, Georgia got revenge, toppling the Tigers 28-7 for its first SEC championship since 2005. Now, Georgia is aiming for its first national title since 1980

Biggest Oklahoma strength: Through 13 games, Oklahoma has had one of the best offenses ever, and it's done so after losing Heisman finalist wideout Dede Westbrook and star tailbacks Joe Mixon and Samaje Perine. The Sooners have one of the nation's best offensive lines, led by left tackle Orlando Brown, and their protection has allowed Mayfield to do what he does best at an even higher level. Mayfield, the Heisman Trophy winner, is a master of creating, of moving around and patiently waiting to make plays. He's also, for three years, been a perfect match for the Air Raid offense of Riley, who spent the past two years as offensive coordinator before becoming head coach. Mayfield is on pace to break the single-season FBS passer rating record … which he already holds because of his performance in 2016. He has completed 71 percent of his passes for 4,340 yards, 41 TDs and five INTs, leading an offense that averages 8.4 yards per play. The Sooners, who have also gotten a second-half breakout from running back Rodney Anderson to complement Mayfield, could be the first offense to average over eight yards per play in a season since Hawaii in 2006. They have explosive playmakers, they make big plays and they have one of the most accomplished quarterbacks in college football history.

Biggest Oklahoma weakness: Simply saying that Oklahoma's biggest strength is the offense in general and its biggest weakness is the defense in general seems elementary, but it's also accurate. Alabama, Clemson and Georgia all rank in the top six nationally in yards per play allowed. The four playoff teams all finished in the top five in the category last year. Oklahoma's defense is a significant outlier: It ranks 71st in yards per play. (The 2015 playoff-bound Oklahoma defense finished 15th.) Of the eight units in the playoff, the Oklahoma defense has clearly been the weakest. The Sooners have been particularly inconsistent in pass coverage, and although they played better down the stretch, two of their late-season games were against Kansas and West Virginia without Will Grier. There's talent here, led by linebacker Ogbonnia Okoronkwo and his 17 ½ tackles for loss, but this is a beatable defense that can be susceptible to big plays.

Biggest Georgia strength: It's hard not to compare Kirby Smart's Georgia team to some of the Alabama teams he was a part of under Nick Saban. The Bulldogs aren't as overwhelmingly dominant as the best Crimson Tide teams on defense, but they're built similarly: They rely on a physical running game with a deep stable of running backs, and they rely on an excellent defense. It's all put true freshman QB Jake Fromm in an excellent situation to succeed. A question mark heading into this season, the offensive line made a giant leap forward just about every game, except for the regular-season loss to Auburn. It's allowed Georgia to pummel opponents by throwing senior running backs Nick Chubb and Sony Michel and freshman D'Andre Swift at them. The Bulldogs rank 10th in rushing yards per game and eighth in yards per rush, with Chubb at 1,175 yards and Michel on the verge of joining him in the thousand-yard club. Meanwhile, led by linebacker Roquan Smith, the Georgia defense ranks sixth in passer rating allowed and has given up only six rushing touchdowns. This team is loaded with experience, beyond the fact that it's trying to become the first team since Oklahoma in 1985 to win a national title with a true freshman starting quarterback. But that experience has allowed Georgia to put together the ideal type of team around a young QB.

Biggest Georgia weakness: Georgia's strengths might not be as impressive as the biggest strengths of other playoff teams, but it lacks glaring weaknesses. The biggest trouble spot to point to happened in the one loss: Auburn's defensive front broke down the Georgia offensive line, contained the running game and put Fromm in difficult situations. Fromm has mostly been excellent this season, ranking fourth nationally in passer rating and second in passer rating on third downs. He averages 9.4 yards per attempt and has thrown only five picks. Still, he's also been put in manageable situations, which is why he's attempting only 17.7 passes per game. If Georgia falls behind Mayfield and Oklahoma's prolific offense, there will be a lot of pressure put on Fromm's arm that he hasn't had to deal with much before. It can't afford to let Oklahoma dictate the pace of the game. Georgia needs its running game to succeed.

Prediction: Oklahoma 34, Georgia 27. Georgia is the more complete team and has the nation's defensive player of the year in Smith. Still, Oklahoma has Mayfield, and after the regular season he had, it's hard to pick against the Heisman Trophy winner showing up with another big performance on a big stage.

Sugar Bowl

No. 1 Clemson vs. No. 4 Alabama

8:45 p.m. ET, ESPN
Announcers: Joe Tessitore, Todd Blackledge, Holly Rowe and Laura Rutledge

Matchup history: It's not the same postseason game, but this is still only the second time that the same two teams have met in the postseason three years in a row. First, it was Ohio State and USC in back-to-back-to-back Rose Bowls from 1972-74. Now, it's Clemson and Alabama in the playoff three straight years. Alabama beat Clemson 45-40 for the national title in 2015. Last year, Clemson beat Alabama 35-31 for the national title on Deshaun Watson's touchdown pass to Hunter Renfrow with one second left -- the Tigers' first win over the Crimson Tide since 1905. Now, they'll meet in a playoff semifinal after splitting the first two meetings in this postseason series. Overall, Alabama leads the all-time series 13-4: Clemson won the first three games from 1900-05, Alabama won 13 in a row spread out over the next century and the Tigers finally won again a year ago in Tampa.

How Clemson got here: After saying goodbye to Watson, the best player in school history, Clemson ended up securing the No. 1 seed in the playoff anyway in its attempt to defend its national title. With QB Kelly Bryant injured, the Tigers lost at Syracuse on a Friday in mid-October, but otherwise they marched through the season unblemished. They had 10 sacks in a 14-6 win over Auburn. They won by double-digits on the road at Louisville, Virginia Tech and South Carolina. They won at N.C. State to secure the ACC Atlantic. They took care of business against Florida State. And they dismantled Miami in the ACC championship game. Dabo Swinney and his staff have repeatedly brought in loads of blue-chip talent, and it's paying off for a program that continues to reload as it becomes a sustainable national power.

How Alabama got here: It's been a somewhat unusual season for Alabama. The usual part? The Crimson Tide are 11-1 with nine wins by double digits, a top-10 running game and a defense that leads the nation in yards per play allowed. That's all pretty typical for Alabama under Nick Saban. The unusual part? The Crimson Tide barely escaped Mississippi State and lost by 12 at Auburn in their last two SEC games, didn't win the SEC West and don't have as impressive a resume as they usually do. That's not all their fault, of course: They beat Florida State 24-7 in what was supposed to be the biggest opening game ever; the Seminoles ended up finishing 7-6 as the season's most disappointing team. Still, instead of easily playing its way into the playoff, Alabama had to debate its way in as a team that didn't win its division.

Biggest Clemson strength: It couldn't be more obvious: It's the defensive front, and especially the defensive line. The linebackers do deserve credit, too, as Kendall Joseph and Dorian O'Daniel lead a somewhat underrated unit. But the star power is up front on arguably the nation's best unit: Austin Bryant, Dexter Lawrence, Christian Wilkins and Clelin Ferrell, who form a star-studded line overflowing with NFL talent. That's been a trend for Clemson, which continues to reload up front. Lawrence, a sophomore, looks like a top-five talent in the 2019 NFL Draft. Wilkins is a versatile star. And Ferrell and Bryant have combined for 31 ½ tackles for loss. Clemson had 10 sacks against Auburn and averages a national-best 3.4 sacks per game. The Tigers allow just 3.1 yards per rush, and the pressure generated up front has played a big role in them ranking fifth in defensive passer rating. Overall, the Clemson defense ranks second in yards per play allowed, behind only Alabama.

Biggest Clemson weakness: Two years ago, Watson had 478 yards of total offense and led Clemson to 40 points against Alabama. The Tigers lost anyway. Last year, Watson had 463 yards of total offense to lead Clemson to a win that came as a result of a touchdown drive in the final two minutes. In the past 10 years, Alabama has allowed six 400-yard passing games by opposing quarterbacks. Two of those six were by Watson in the national title game, and Clemson needed all of that production to split a couple close games. Bryant has done a terrific job replacing Watson, but there is no replacing Watson -- particularly Watson's performances against Alabama. Bryant has completed 67.4 percent of his passes for 2,678 yards, 13 TDs and six INTs with a modest average of 7.4 yards per attempt, and he has rushed for 646 yards and 11 TDs. He's a talented dual-threat player who has led Clemson to a 12-1 record. But can he do enough to beat Alabama? The Tigers quietly rank just 47th in yards per play on offense.

Biggest Alabama strength: This can't help but read similarly to Georgia's blurb above in the Rose Bowl preview. Alabama is often dominant in the running game, and it's almost always dominant across the board defensively. The Crimson Tide have an impossibly deep backfield on offense featuring prolific running quarterback Jalen Hurts; five-star recruits Damien Harris, Bo Scarbrough and Najee Harris; and the versatile Joshua Jacobs. Scarbrough hasn't had the big season that was expected of him after his late-season 2016 emergence, but the talent here is undeniable. Alabama ranks eighth in rushing yards per game and fifth in yards per rush. Defensively, Alabama has shown cracks -- especially with injury problems down the stretch -- and yet it ranks first in yards per play, first in points allowed, second in passer rating, first in yards per pass attempt and first against the run. Depth and the pass rush have taken hits, but Alabama especially owns an excellent secondary and continues to play at a high level. Alabama's problems aren't like anybody else's problems, particularly on defense.

Biggest Alabama weakness: Hurts has flashed improvement as a passer. He's thrown only one interception, he averages 8.7 yards per attempt (1.4 more than last year) and he was terrific down the stretch in the dramatic win over Mississippi State. Still, questions remain about Hurts and the diversity of this passing attack under new coordinator Brian Daboll. Calvin Ridley has 55 catches; he's the only Alabama player with more than 14 catches over 12 games. The passing game is often Ridley-or-nothing, after ArDarius Stewart and O.J. Howard, who are gone, played big roles last year, too. The passing questions create questions about Alabama on third down, especially against such a talented Clemson defensive line. The Tide rank 49th in third-down conversions, and they converted just 6 of 21 in their last two SEC games against Auburn and Mississippi State. Last year, they converted just 6 of 29 in two playoff games, including 2 of 15 in the national title game loss. That was the biggest stat of the game, as Alabama's inability to sustain drives allowed Clemson to wear down the Crimson Tide defense, run 99 plays and stage a comeback.

Prediction: Alabama 27, Clemson 24. It's going to be difficult for this one to measure up to the classics of the past two years, but it's also hard to see either team pulling away. Despite the questions about Alabama's passing game, it has still been the more efficient team on offense. It can win a close one.

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