NORMAN, Okla. -- Iowa State's Joel Lanning was right in the middle of the action Saturday against No. 3 Oklahoma.

Lanning made plays as a linebacker -- recording eight tackles and a sack -- and as a quarterback, rushing for 35 yards and passing for 25.

Then, at the end, there was Lanning in the middle of a Cyclones' celebration after an stunning 38-31 upset win on Saturday.

"There's been a lot of adversity around Iowa State for a long time and a lot of cloud around it," Iowa State coach Matt Campbell said. "And I think our kids said, 'I'm sick of it.'"

Iowa State snapped Oklahoma's 17-game conference winning streak, dating to the 2015 season.

The Cyclones even planted a state of Iowa flag at midfield, much like quarterback Baker Mayfield planted an OU flag after the Sooners' win at Ohio State last month.

"It's expected," Mayfield said. "I'm sure I will get comments of 'Iowa State is my dad' or something like that. ... I don't worry about what they're doing. We have to go back to work."

Iowa State (3-2, 1-1 Big 12) entered as about a 30-point underdog and hadn't beaten Oklahoma (4-1, 1-1) since 1990, a streak of 18 consecutive losses. What's more, the Cyclones didn't have starting quarterback Jacob Park, who didn't make the trip. School officials announced he was taking a leave from the team for undisclosed "medical concerns."

The Cyclones had to go with quarterback Kyle Kempt, who had thrown for just 15 yards during his college career and had not attempted a pass this season entering the game. But he passed for 343 yards and three touchdowns against the Sooners, completing 18 of 24 passes.

He also got some help from Lanning, who came in to spell Kempt at quarterback. In the offseason, Lanning had moved to middle linebacker when he lost the starting quarterback job to Park. Lanning had started 14 games at quarterback during his career.

"I think Cyclone nation will remember Joel Lanning for a long, long time," Campbell said. "What he's doing is unheard of."

But while Lanning made big plays on both sides of the ball, it was Kempt who made the final big offensive play, hitting Allen Lazard on a fade route with 2:19 remaining to put the Cyclones ahead for good. Lazard went up over Oklahoma safety Chanse Sylvie and cornerback Jordan Thomas to haul in the pass.

The Sooners had one more chance to tie it but Lanning made a big tackle on second down to keep running back Trey Sermon from picking up the first down. Mayfield threw back-to-back incompletions to seal the upset.

The Sooners led by 14 points three times before the struggle started on both sides of the ball.

After scoring on its first four drives, Oklahoma came away from the next four drives with no points, letting the Cyclones back into the game.

Iowa State's comeback kicked into high gear when a fumbled exchange by the Sooners at the Cyclones 5 ended what looked destined to be another OU touchdown drive that would have put Oklahoma up by 15.

"When you let teams hang in there like that and teams make some plays and get a little bit of momentum, you can get beat," Oklahoma coach Lincoln Riley said.

Instead, Iowa State took advantage of Lanning's fumble recovery and quickly tied the game, thanks in part to a pass interference penalty and then Kempt's 28-yard touchdown to Marchie Murdock.

Kempt then hit Lazard for a two-point conversion to tie it.

Iowa State's defense made another critical stop just before half after the Sooners used two timeouts to get the ball back with a chance to extend their lead from 24-10.

But instead, it was the Cyclones that took advantage of the extra time, holding the Sooners to a three-and-out and then getting the ball back with 26 seconds remaining before half.

Kempt immediately hit Hakeem Butler for a 54-yard gain to set up a field goal that cut Oklahoma's lead to 11 at the break.

After beating Ohio State on Sept. 9, the Sooners have now stumbled through three consecutive games, though they beat Tulane and Baylor before losing to Iowa State.

"I think it's a sense of complacency," said Mayfield, who was 24 of 33 for 306 yards and two touchdowns. "We've been talking about it. It's not like it hasn't been apparent. We've let teams come back in games."

NOTES: Iowa State LB/QB Joel Lanning became the first Cyclones player since Dave McCurry in 1971 to play significant snaps on both sides of the ball. ... Oklahoma NG Matt Romar missed his third consecutive game after suffering an injury early in the Sept. 9 game at Ohio State. .... Sooners RB Abdul Adams and WR CeeDee Lamb left the game in the first quarter with injuries. Adams appeared to injure his ankle while Lamb hurt his shoulder on a touchdown catch. ... Iowa State hosts Kansas on Saturday. ... The Sooners play Texas in Dallas.