Oklahoma had four turnovers and Kansas State had none as the Wildcats upset formerly No. 3 Oklahoma 38-35 in Norman Saturday in front of only 22,000 fans.

One more loss in the Big 12 and OU’s chance to win the Big 12 Conference would probably evaporate. And the loss to K-State could be very damaging for Oklahoma’s hopes for returning to the College Football Playoff.

Freshman QB Spencer Rattler was brilliant for OU in the first half but the Sooner offense sputtered in the second. The Sooner running game was ineffective throughout the game.

OU travels to Iowa State Saturday for a crucial conference match up.

Iowa State (1-1, 1-0 in the Big 12) edged past TCU 37-34 in Fort Worth. ISU’s Breece Hall ran 18 times for 155 yards and three touchdowns. ISU quarterback Brock Purdy hit 18 of 22 pass attempts for 211 yards and one touchdown.

It was a bounce back win for Kansas State, who had lost to Arkansas State in the season opener.

“It’s a big win with the circumstances we faced and some of the adversity our guys have gone through,” Kansas State coach Chris Klieman said. “Excited that we fought for four quarters. I trust those guys, I believe in them, the biggest thing is they need to believe in themselves. They know we want to give them opportunities, and they made the most of them today.”

The win was Kansas State’s first ever on the road over a team ranked in the top three of the Associated Press poll. The Wildcats had lost their last 16 games against Top 3 teams in a row.

“In the second half we just played very poor football,” Oklahoma coach Lincoln Riley said. “We didn’t do the things we needed to do to put this game away.”

Rattler hit 30 of 41 passes for 387 yards (9.4 yards per catch) and 4 touchdowns. But his three interceptions were game changers.

“He had the one reckless interception in the first half where he just threw the ball up. That was frustrating. Other than that, he was really good in the first half,” Riley said. “And then we just couldn’t keep him quite comfortable enough in the pocket. I didn’t think he was very comfortable there the entire day. Moved around, missed a few things, missed a couple throws. Made a lot of big plays, had several big plays taken back by penalties.”

OU went for a quarterback sneak in the second half and failed to pick up a yard and Kansas State blocked a punt in the fourth quarter to set up a score.

KSU quarterback Skylar Thomson outplayed Rattler, hitting 18 of 25 attempts for 334 yards (13.4 yards per catch) and one touchdowns. But K-State had no turnovers.

KSU running back Deuce Vaughn caught four passes for 129 yards and almost scored on a long reception before being tackled at the one yard line.

OU couldn’t hang on to a significant lead.

“It’s glaring. You emphasize it, you talk about it, you make the guys aware of it,” OU defensive coordinator Alex Grinch said. “You try to create those situations obviously in practice. You don’t hope for better results in the future and say ‘well we just didn’t get it done.’ It’s something we gotta continue to evaluate and gotta do a better job of.”

“Elite teams and good defenses, which clearly we’re not, are able to have a resolve, don’t let one play beat you, don’t let one play turn into two, and have an energy regardless of what’s going on, can create their own emotion, create their own energy,” Grinch said.

 “Again, it all comes back down to coaching. It’s something that you can’t ignore. It’s a results business. The facts are the facts. The results indicate that we, as a coaching staff, are incapable of getting our guys to do it. So we’ve got to do a better job.”

Seth McGowan led the Sooners in rushing with 73 yards on 13 carries. But his fumble in the third quarter gave the trailing Wildcats a big boost and stalled an OU drive.

 T.J. Pledger, in his first game of the season, had only 41 yards on 13 carries.

Drake Stoops, son of former OU coach Bob Stoops, caught three passes for 93 yards and one touchdown. Tight end Austin Stogner had five catches for 83 yards and Jeremiah Hall had two catches for 29 yards and one touchdown. Freshman Marvin Mims caught five passes and scored two touchdowns.

OU led 21-7 at the half but was outscored 17-0 in the final quarter. It is the second year in a row that Kansas State has defeated Riley and the Sooners.

OU won the statistical battle with 28 first downs to KSU’s 10 and 517 yards of total offense compared to 400 for K-State.

Before Saturday, OU had won 53 straight games when leading after the third quarter. The last such loss under the circumstance came to Oklahoma State in 2014 (OU led 28-14 at home going into the fourth quarter but lost 38-35 in overtime).

Oklahoma lost its Big 12 opener for the first time since 2012 (24-19 defeat to Kansas State). Prior to today, OU had won seven straight Big 12 openers and 11 of the previous 12.

OU has lost consecutive games against Kansas State for the first time since the 1996-97 seasons (KSU won five straight from 1993-97). This marks the first time the Sooners have been beaten by the same program in consecutive years since the 2013-14 seasons (Baylor).