NORMAN, Okla. -- With his best receiver sidelined, Baker Mayfield still boosted his Heisman Trophy resume.

Mayfield passed for 288 yards and three touchdowns, and No. 9 Oklahoma defeated No. 10 Oklahoma State 38-20 on Saturday in a matchup that decided the Big 12 champion and likely guaranteed the Sooners a trip to the Sugar Bowl.

Mayfield performed well throughout, despite finishing the game without Biletnikoff Award finalist Dede Westbrook. The speedster caught four passes for 111 yards before being knocked out of the game in the second quarter on a crushing hit by Oklahoma State safety Jordan Sterns. Mayfield threw two touchdown passes after Westbrook left the game, and the offense didn't miss a beat, finishing with 629 yards.

"He was just fantastic, he was just exactly what he needed to be," Oklahoma coach Bob Stoops said of Mayfield. "He gave our guys chances to make plays, he handled the ball great himself, had a few key runs for us, threw the ball. The guy's really, really talented. To be able to do what he did, there's not many guys who could do what he did today."

Mayfield finished fourth in the Heisman balloting last year, but he didn't get an invitation to New York for the ceremony. He wants to go this year, and he wants Westbrook to get an invitation, too.

After the game, Mayfield wore a pin from the school with both his and Westbrook's names on it. Mayfield crossed out his own name with a marker to make sure Westbrook wasn't forgotten.

"Dede is the best player in the country," Mayfield said. "I still want to hold Dede's hand all the way to New York."

Mayfield should be a Heisman front-runner heading into next season, too. He said after the game that he plans to return for his senior season.

"Coming back, be here for another year," he said. "Opportunity for a three-peat (Big 12). The ultimate goal is why I came here -- to win a national title."

Samaje Perine rambled for 239 yards on a career-high 37 carries and Joe Mixon caught a touchdown pass and busted a 79-yard touchdown run for the Sooners (10-2, 9-0 Big 12, No. 9 College Football Playoff).

It was the second straight time the teams met in the regular-season finale to determine the conference champion. Oklahoma beat the Cowboys 58-23 last season.

In this year's showdown, Mason Rudolph completed just 11 of 25 passes for 186 yards for Oklahoma State (9-3, 7-2, No. 10 CFP). His top target for the season, James Washington, caught just two passes for 50 yards on eight targets.

"Just a rough day," Rudolph said. "I'll take all the responsibility for the lack of production, especially in the second half. Obviously, it needed to be better."

THE TAKEAWAY

OKLAHOMA STATE: It was an especially bitter defeat for the Cowboys, who have become so close to turning the tide against their biggest rival. The Cowboys, who last won the Big 12 in 2011, fell to 2-10 against the Sooners under coach Mike Gundy. Even with Westbrook out and Perine being knocked out briefly after a helmet-to-helmet hit, the Cowboys couldn't keep the momentum.

"They made too many big plays," Sterns said. "That's a great football team with big playmakers."

OKLAHOMA: The Sooners added a second straight win over a highly ranked opponent, but it likely wasn't enough to get them into the College Football playoff for the second straight year.

"Probably, realistically, more needed to happen last week to give ourselves a better opportunity, but that's past," Stoops said. "Whatever they're going to decide, they'll decide."

POLL IMPLICATIONS

OKLAHOMA STATE: Likely won't fall too far with a road loss against a Top 10 team , especially with so many other top teams playing each other.

OKLAHOMA: Not much space to move up. The Sooners were already ahead of Colorado, which lost to Washington on Friday.

UP NEXT

OKLAHOMA STATE: Bowl game to be determined.

OKLAHOMA: The Sugar Bowl on Jan. 2 unless the Sooners make the College Football Playoff.