NORMAN, Okla. - Adrian Peterson rushed for 51 yards and a touchdown before leaving with an injury in the second quarter, putting a damper on Oklahoma’s best offensive performance of the season and 43-21 victory over Kansas State on Saturday night.

Kejuan Jones added two touchdown runs in relief of Peterson, and Rhett Bomar ran for one score and passed for another as Oklahoma (2-2, 1-0 Big 12 Conference) won its Big 12 opener for the sixth straight year.

Peterson, the Heisman runner-up last year, left the game late in the second quarter and sat on a table on the sidelines as trainers worked on his right foot. He tried to stand once, but took a seat again as trainers continued to examine him. At halftime, he walked off the field on his own, but was limping noticeably.

He returned to the sidelines in the second half, but did not play.

The Sooners will face No. 2 Texas next Saturday in Dallas.

Oklahoma, playing as an unranked team for the first time since 1999, were fine without Peterson against the Wildcats.

Jones scored on a 3-yard run to give Oklahoma a 19-0 halftime lead, and the Sooners built on it with help from numerous mistakes by Kansas State (3-1, 0-1).

Freshman Reggie Smith’s first career interception set up an 8-yard touchdown run by Bomar on the Sooners’ first possession of the second half and a 17-yard punt by Kansas State’s Tim Reyer led to Jones’ second touchdown run — a 2-yard plunge that made it 33-7.

At least that time Reyer was on the field.

In the first quarter, the Sooners grabbed a 9-0 lead when the Wildcats snapped the ball out of the back of the end zone on a punt attempt with Reyer still on the sidelines.

On the Sooners’ previous possession, they took advantage of a third-down personal foul by K-State linebacker Brandon Archer and took the lead on Peterson’s 22-yard run.

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Reyer’s next punt attempt went only 8 yards after Jacob Gutierrez partially blocked it, and Garrett Hartley connected on a 29-yard field goal seven plays later to make it 12-0.

Jordy Nelson spun away from a defender and scored on a 73-yard reception, and Rashaad Norwood had an 11-yard TD catch for Kansas State, which was trying to match its win total from last season.

Ayo Saba added a 1-yard TD run in the fourth quarter.

Thomas Clayton, who was held out of last week’s game after a campus incident involving a parking official, started and had only 8 yards on 12 carries. He had 329 rushing yards in the Wildcats’ first two games.

Bomar threw his first career touchdown pass on a 4-yard toss to Joe Jon Finley in the fourth quarter and finished with 139 yards on 12-for-22 passing. He also ran for 67 yards on eight carries.

Allen Webb threw for 177 yards with two touchdowns and one interception for Kansas State.