The last time Iowa State beat Oklahoma, the Big 12 didn't exist. Until Saturday, that is.

The long wait is over now, as the Cyclones shocked the No. 3 Sooners with a 38-31 comeback win on the road in Norman.

Oklahoma entered this year's game with a 74-5-2 record against Iowa State. It had won 18 in a row and had lost only once in the series since 1961. The one win came in 1990, a 33-31 Iowa State victory when the two played in what was still the Big Eight. Despite trailing by two touchdowns for much of the first half against a presumed playoff contender with a Heisman contender quarterback, the Cyclones ended that streak on Saturday.

The Cyclones pulled off the most surprising upset of the season so far without starting quarterback Jacob Park, who took a leave of absence from the team because of a medical issue. With Park out, senior Kyle Kempt was the primary quarterback, throwing for 343 yards and three TDs to outplay Baker Mayfield. He wasn't the only Iowa State quarterback to make headlines, either, because the Cyclones also utilized quarterback-turned-linebacker Joel Lanning as a two-player.

Lanning entered the game with 2,537 passing yards and 849 rushing yards in his career, but he switched to linebacker before the season and had 46 tackles in his first five games. On Saturday, with Iowa State needing him on both sides of the ball, Lanning finished with 25 passing yards and nine carries for 35 yards on offense. On defense, he had eight tackles and made several key plays, including a pivotal fumble recovery.

Oklahoma led 24-13 at halftime. After an Iowa State field goal, the Sooners drove to the Cyclones' five-yard line, but Mayfield and Trey Sermon fumbled an exchange, and Lanning fell on it. Iowa State needed only seven plays to go 94 yards and capitalize on the mistake, thanks to a 22-yard David Montgomery run, a 35-yard Allen Lazard catch and a 28-yard Marchie Murdock touchdown from Kempt.

The sequence set the tone for the rest of the game. Oklahoma missed a field goal next, and Iowa State quickly marched downfield, with Kempt finding Trever Ryen for a 57-yard TD to take the lead.

Oklahoma responded with a touchdown drive, giving Iowa State the ball in a tie game with 7:18 left. Lanning had an eight-yard run and a five-yard run in Sooners' territory. Two plays later, on a third-and-seven, Kempt launched a ball into the end zone for Lazard, who brought it down for the go-ahead score.

On the ensuing drive, the Cyclones forced a fourth-down Mayfield incompletion to seal the upset win.

For a while, the early-afternoon time slot on Saturday looked rather dull. No. 2 Clemson, No. 4 Penn State, No. 5 Georgia and No. 12 Auburn won with ease. Iowa State visiting No. 3 Oklahoma without its starting quarterback appeared to be as unlikely a spot as any for an upset, given the teams' history, given that Oklahoma already won convincingly at Ohio State -- the best win anybody had in the first five weeks of the season -- and given that Iowa State hasn't won more than three games in a season since 2012.

Instead, the Cyclones pulled off the upset as 31-point underdogs with a backup quarterback, a two-way quarterback/linebacker and a near-perfect second half that included touchdown drives of 94, 73 and 75 yards.

It's a huge blow to Oklahoma's playoff hopes. It's a huge blow to Mayfield's Heisman hopes. On the other side, it was a memorable, history-making day in Norman, the type of out-of-nowhere upset that always seems to pop up on what appeared to be an unremarkable afternoon of football.

Six years after Iowa State ruined the national championship hopes of then-No. 2 Oklahoma State in 2011, the Cyclones own another top-five win over a Big 12 heavyweight, made even more memorable by the presence of a senior leader playing both linebacker and change-up quarterback. 

There's no more series losing streak, no more talk about not winning since 1990. At Iowa State, all that matters right now is one of the biggest wins in school history.

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Contact Matt at matt.brown5082@gmail.com and follow him on Twitter @MattBrownCFB and Facebook.