Oklahoma committed too many mistakes and lost 31-30 to Kansas State at Owen Field in Norman on Saturday.
OU had two missed field goals, a blocked extra point, and two interceptions, all of them costly, to lose to the Wildcats for the second straight time in Norman.
On OU's second possession of the game, two things went against the Sooners on the same play.
Fullback Aaron Ripkowski was ejected for targeting when he lowered his helmet to make a block.
It freed up quarterback Trevor Knight to get a few yards around the right side, but Knight went down short of the first down and was slow to get up.
After trainers checked him out, Knight ran to the lockerroom.
The drive continued with Cody Thomas taking over at quarterback.
On Thomas' first snap, Alex Ross ran for 41 yards, and the Sooners capped the scoring drive on a 2-yard touchdown run by Samaje Perine to give OU a 7-0 lead with 4:58 to play in the first quarter.
Perine had 89 yards rushing on 24 carries.
K-State responded in less than a minute, going 75 yards in just three plays, with Jake Waters passing to Glenn Gronkowski for a 62-yard touchdown to tie the game at 7.
Knight returned at quarterback on OU's next possession, but the Sooners couldn't make a first down.
Early in the second quarter, KSU punted to the Sooner 2-yard line, and that field position paid off quickly for the Wildcats.
After a delay of game penalty backed OU up to their own 1-yard line, Knight was intercepted by Danzel McDaniel on a pass to the left flat, and McDaniel waltzed into the end zone from 3 yards out to put K-State up 14-7 with 14:04 to play in the second quarter.
The Sooners responded in just two plays.
First, Knight passed over the middle to Blake Bell for 22 yards.
Then Knight went deep to Sterling Shepard, who was wide open for a 47-yard touchdown to tie the game at 14 with 13:36 left in the first half.
Shepard tied OU's single game record for receptions with 15, for 197 yards.
Kansas State answered, going 75 yards in nine plays, with Waters passing to the post to Tyler Lockett for a 9-yard touchdown to give the Wildcats a 21-14 lead with 9:33 to play in the half.
Oklahoma responded with a drive to a field goal, as Michael Hunnicutt kicked a 38-yarder to make it 21-17 Wildcats with 4:24 to play in the second quarter.
The kick was Hunicutt's 71st career field goal, tying former Colorado kicker Mason Crosby for the Big 12 record.
On the drive, Shepard fell on a photographer's lense while trying to make a catch in the back corner of the end zone.
Shepard was seen limping to the lockerroom right before halftime.
OU forced another K-State punt and with under a minute to play had a final chance to score in the first half.
Pass plays to Austin Bennett and Miciah Quick got OU to the 15-yard line with 3 seconds left in the half.
Hunnicutt had a chance to break the Big 12 record for career field goals, but he missed wide left from 32 yards and K-State led 21-17 at halftime.
Kansas State got the ball to start the second half and on the first snap of the half, Waters ran for 53 yards to the OU 22.
Waters appeared to injure his shoulder as he went down, and after Matthew McCrane kicked a 27-yard field goal, Waters went to the lockerroom to get checked out.
Trailing 24-17, Oklahoma went on a 7-play, 64-yard drive, with Knight passing to Bell for a 4-yard touchdown to tie the game at 24 with 9:32 to play in the third quarter.
Knight was 26 of 32 for 318 yards and 3 touchdowns.
Kansas State once again responded immediately.
Demarcus Robinson picked up 38 yards on a running play, and a few plays later, Waters kept for a 4-yard touchdown to put the Wildcats back on top 31-24 with 6:57 to play in the third quarter.
Waters passed for 225 yards and ran for 51 more on 10 carries.
OU threatened to answer, moving the ball inside the Wildcat 20, but the Sooners got too fancy.
Durron Neal attempted an reverse flanker pass, but it was intercepted by Morgan Burns in the end zone for a touchback.
K-State moved the ball into OU territory, but had to punt as the quarter came to an end.
Oklahoma started the fourth quarter with the ball on their own 7-yard line.
The Sooners went 93 yards in 11 plays, with Knight passing to Durron Neal for a 9-yard touchdown.
The extra point was blocked, and the Wildcats still led 31-30 with 10:35 to play in the fourth quarter.
For the first time in the game, OU's defense then held Kansas State to three downs and out and the Wildcats punted to the OU 27.
The Sooners used a heavy dose of Perine to move down the field, giving him the ball 6 times for 44 yards to get to the KSU 1.
On third and goal, they gave Perine the ball again, but the Wildcats stopped him for a loss of 2.
OU brought on Hunnicutt for a 19-yard field goal to give OU the lead, but he hooked it left and K-State still led 31-30 with 3:53 to play.
Kansas State never gave the ball up again, converting a 3rd and 3 with a 6-yard pass from Waters to Curry Sexton.
OU had more first downs than K-State, 30-17, and outgained the Wildcats 533-385 in total yards.
The Wildcats improve to 5-1, 3-0 in the Big 12.
OU drops to 5-2, 2-2 in the conference.
Oklahoma is off next weekend before visiting Iowa State November 1.