NORMAN, Okla. (AP) -- After waiting weeks to get back into Oklahoma's lineup, Adrian Peterson needed just a little more patience to get himself a big rushing day.

Peterson ran for a season-high 237 yards, including two long touchdowns in the second half, and Rhett Bomar threw three touchdown passes to lead Oklahoma to a 42-14 victory over Oklahoma State on Saturday.

The Sooners' third straight win in the Bedlam rivalry was lackluster until Peterson, the Heisman Trophy runner-up last season, livened things up with an 84-yard touchdown run in the third quarter.

Peterson ran around the right end of the line, passed two downfield blocks and sped into the end zone untouched for the longest run of his career and a 28-7 lead.

"I just slowed down and took my steps," Peterson said. "Actually, the hole, you could have run a diesel through it, it was so big. I just took off."

His previous longest run was an 80-yard score against the Cowboys in the Sooners' 38-35 win last year in Stillwater.

Peterson said his running backs coach, Cale Gundy, was telling him to keep grinding for yards and eventually it would pay off. He had only 27 yards on 11 first-half carries and then set an Oklahoma record for rushing in a half with 210 yards.

"The holes opened up, and I just popped 'em," Peterson said.

After Julius Crosslin's second short touchdown run pulled Oklahoma State (4-7, 1-7 Big 12) back within 28-14, Peterson responded on Oklahoma's next offensive play with a 71-yard run down the left side.

Bomar added a 55-yard touchdown pass to Manuel Johnson to extend the lead to 42-14. He finished with 206 yards on 13-for-21 passing with one interception.

After a three-game span in which he rushed for only four total yards, Peterson missed the first game of his Oklahoma career Oct. 22 against Baylor. He's had two touchdowns in each game since and topped it off with the third-best rushing total of his young career against the Cowboys.

"A.D. was just incredible again," Stoops said. "The guy's getting his ankle back and it just gets better and better. I still don't believe it's all the way back."

"Aw, no, I'm not healthy," Peterson added. "I'm not 100 percent, but I'm getting there."

By winning the rivalry's 100th game, Oklahoma (7-4, 6-2) now holds a 77-16-7 edge in the series.

The game lacked the fire of recent years, with Oklahoma entering the game unranked. The Sooners had been in the top five for the last five meetings, and Oklahoma State twice pulled upsets.

Even without the high stakes, a brief skirmish erupted about 45 minutes before the game when the teams encountered each other on the southeast corner of Owen Field, but there was a lot more noise than physical contact.

"They were just bouncing back and forth at each other," Stoops said. "I don't think there were any punches or anything."

Oklahoma grabbed a 21-0 lead on a 27-yard touchdown run by Allen Patrick and Bomar's touchdown passes to Juaquin Iglesias and James Moses, but the offense slowed considerably after that.

The Sooners had only three first downs on their next seven possessions, leading up to Peterson's first big run. One second-half drive stopped when Peterson was tackled for no gain on fourth-and-1, and another was halted when Peterson lost a yard on third down and the Sooners had to punt.

"The more and more you feed it to him, he gets stronger and stronger," Stoops said. "You just keep at it and eventually, you hit one of those seams, and we did a few times."

The Cowboys could never really get their offense going with Al Pena starting at quarterback in place of Bobby Reid. Pena threw for 351 yards -- the fifth-highest total in school history -- after replacing Reid in a 44-34 loss at Baylor last week, but he was largely ineffective against the Sooners.

Oklahoma State had only one first down and zero yards of total offense on its first seven possessions before breaking through when Pena scrambled and tossed the ball to Luke Frazier, who raced to the Oklahoma 4 for a 56-yard gain. Crosslin followed with a 1-yard TD run to pull Oklahoma State within 21-7.

"I don't think there's any doubt we didn't come prepared to play," said Oklahoma State coach Mike Gundy, Cale's brother. "I was excited for the team when we got to the end of the fourth quarter and punched it in there to make it 28-14 before Peterson took off on a long run.

"We were making headway until he took the game over," he said.

Pena threw for 126 yards on 10-for-27 passing with one interception.

Mike Hamilton, who needed 59 yards to become the first Oklahoma State freshman to run for 1,000 yards, finished well short with 20 yards on 11 carries. He still holds Oklahoma State's freshman rushing record.