NORMAN, Okla. -- Baker Mayfield and Dede Westbrook have become a dynamic duo for the Oklahoma Sooners.

Mayfield completed all but six of his 31 passes for 346 yards and four touchdowns, Westbrook had nine receptions for 184 yards and three scores and No. 19 Oklahoma pulled away to beat Kansas State 38-17 on Saturday.

One week after Mayfield passed for 390 yards and Westbrook had a school-record 232 yards receiving, they were electric once again as Oklahoma (4-2, 3-0 Big 12) won its third straight game after starting out 1-2.

When Mayfield hit a wide open Westbrook for an 88-yard touchdown -- the longest pass play at home and fourth-longest overall in Oklahoma history -- in the fourth quarter, it was Westbrook's eighth TD in the last three games, a new school record.

"Two talented guys," Oklahoma coach Bob Stoops said. "Of course, Baker's just great. I'm just looking at 25 out of 31 -- that's a great day against a good defense. And then Dede's just got that speed and polish in his route running to get open."

With Samaje Perine sidelined by a muscle injury in the first quarter, Joe Mixon stepped up for Oklahoma. He rushed for 88 yards, caught three passes for 34 yards and a touchdown and became the first Sooners running back since Joe Washington in 1973 to throw a touchdown pass. The 26-yarder to Westbrook in the second quarter put the Sooners ahead 21-7.

"We trust Joe," Mayfield said. "We were able to come out there and still run the same plays, even when Samaje wasn't out there, so that's why you saw some success in our passing game because those guys were still worried about our run game."

Stoops noted that Perine was held out for precautionary reasons.

"Samaje just had a slight pulled muscle, and if forced to play, he could have," Stoops said. "We wanted to see if we could get away with it, and hopefully allow it to heal this week."

Kansas State (3-3, 1-2) had its own injury issues as starting quarterback Jesse Ertz left for good just after halftime with an apparent problem with his right throwing shoulder. He completed 8 of 14 passes for 68 yards and ended the game as the Wildcats' leading rusher with 40 yards and a touchdown on seven carries.

Joe Hubener came in and threw for 157 yards on 12 of 23 passes, with a spectacular 54-yard touchdown to Dominique Heath early in the fourth quarter that pulled K-State to within 31-17. Heath ended up with seven receptions for 101 yards, both career-highs.

"It's never as good as I would like," Kansas State coach Bill Snyder said of his quarterbacks. "I think Jesse did some good things, Joe did some good things, but they made some mistakes. It's still a work in progress."

TAKEAWAY

Kansas State: K-State entered the game with the Big 12's top defense, allowing just 17.6 points and 310.2 yards per game, but Oklahoma had 21 points less than five minutes into the second quarter and piled up 510 total yards.

"You have to stay aggressive against a defense like K-State," said Oklahoma offensive coordinator Lincoln Riley. "If you start to get conservative and hand it off every time, they will prey on you, and they've done it against everybody, they're one of the best run defenses in the country."

Oklahoma: The Sooners need to keep feeding the ball to Mixon, even when Perine is healthy. Even as Perine's backup, Mixon entered the day ranking fourth in the nation averaging 179 yards per game in all-purpose yards, and put up 177 in this one. His 19 rushes were a career high.

"Joe was sensational running the football," Stoops said, "making a really good defense miss him on a good number of occasions to get extra yards. He ran tough in a lot of instances, caught the ball well, had a big kickoff return, and then goes and throws a touchdown pass."

PLAY OF THE GAME

Which Mixon play to choose? There was the 8-yard touchdown reception where he made a one-handed catch on a short shovel pass from Mayfield and then hurdled over K-State safety Dante Barnett on his way to the end zone, which made it 14-0. Or would it be his 26-yard touchdown pass to Westbrook early in the second quarter?

"We'll have to work on his spiral," Mayfield said of Mixon's pass. "That was a pretty ugly duck, but he got it there, that's all that matters."

UP NEXT

Kansas State: The Wildcats host Texas next Saturday.

Oklahoma: The Sooners visit Texas Tech next Saturday.