EUGENE, Ore. -- It was not pretty, but No. 11 Washington State is still undefeated.

In a game featuring high-powered offenses, it was the Cougars' defense that was the determining factor.

Washington State, facing Oregon's third-string quarterback in freshman Braxton Burmeister, didn't allow the Ducks to score after the first quarter en route to a 33-10 victory Saturday.

The Cougars (6-0, 3-0 Pac-12) allowed only 277 total yards, all while forcing three turnovers and limiting Oregon (4-2, 1-2) to 2-for-17 on third down.

"I thought we ran to the ball well, obviously we got some turnovers that helped because all of their skill players are very fast," Washington State coach Mike Leach said. "I'm proud of the way our team finished -- we did a pretty good job."

Cougars quarterback Luke Falk threw for 282 yards and three touchdowns on 24-of-42 passing. At times, Falk appeared bothered by the size and athleticism of Oregon's defensive line, struggling on third down (2-for-13). Still, his command of the offense led to multiple big plays.

"I thought our defense played well. I didn't think we did enough offensively to show how well they played," Oregon coach Willie Taggart said.

Kyle Sweet recorded seven receptions for 86 yards while Isaiah Johnson-Mack, Jamal Morrow and Renard Bell all caught touchdown passes.

The first two plays of the fourth quarter were the deciding points.

Leading 23-10, Washington State's Marcus Strong picked off an underthrown ball by Burmeister and returned it to the Ducks' 25-yard line. On the next play, Falk hit Johnson-Mack for a touchdown pass to make it 30-10.

"I thought it was big," Leach said. "It was one of those really tight games -- tighter than the score -- and I thought something was going to blow it open."

Leading 13-10 at halftime, Falk and the Cougars marched 75 yards for a score on their first possession of the third quarter. The big play came on third-and-19 from the Cougars' 16-yard line, when Falk converted a first down on a 29-yard back-shoulder throw to Johnson-Mack. Four plays later, Falk completed a 10-yard scoring pass to Renard Bell for the 20-10 advantage.

"Offensively, you always have to execute. We did some good things, did some explosive things," Leach said. "We were more consistent in the second half."

The Cougars added to their lead when kicker Erik Powell hit a 47-yard field goal, one of his four made kicks in the game.

Washington State got the ball back when Burmeister fumbled after being hit on third down. The Cougars recovered at Oregon's 44-yard line, putting Falk in business.

"We didn't tackle well, didn't do our assignments well, had lots of mental errors," Oregon's Troy Dye, who had a game-high 11 tackles, said. "You can't give up 33 points and expect to win."

The Ducks were without five starters, including quarterback Justin Herbert and their top two wide receivers, Charles Nelson and Dillon Mitchell.

Although Oregon got running back Royce Freeman back this week from injury, he was held to 62 yards on 12 carries.

Burmeister finished his first college start by going 15 of 27 with one touchdown and two interceptions. He was sacked four times.

"We had a big thing about how we wanted to make them pass and not and make them run and I thought we did a great job tonight," Cougars safety Hunter Dale said. "We were just more physical."

The game didn't get off to a great start for Oregon.

Before Burmeister took his first snap, the Ducks were hit with back-to-back false-start penalties. After a first down, the drive stalled when facing a fourth-and-1. Oregon went for it but Freeman was stopped short, giving the ball to Falk and Washington State in Oregon territory.

Falk needed just one play to get the Cougars on the board. He hit a check-down pass to running back Morrow, who took the ball 41 yards for the score 2:19 into the game.

The rest of the first quarter belonged to Oregon.

The Ducks, aided by two bad Cougar punts, began two of their drives in Washington State territory. A 20-yard field goal by Aidan Schneider and a 30-yard touchdown pass by Burmeister to Jacob Breeland gave Oregon a 10-7 lead.

Oregon's defense yielded only seven yards the rest of the quarter after the Falk touchdown pass, forcing three three-and-outs.

Washington State tied the game early in the second quarter on a 25-yard field goal by Erik Powell. Powell then gave the Cougars a 13-10 lead when he drilled a 52-yarder midway through the quarter.

NOTES: Freshman QB Braxton Burmeister replaced starter Justin Herbert, who fractured his collarbone last week and is out 4-to-6 weeks... Three NFL scouts (Cleveland Browns, Buffalo Bills and Los Angeles Rams) were in attendance for the game while the BC Lions of the CFL were also at Autzen Stadium. ... Oregon WR Charles Nelson (ankle) went through warmups fully dressed but determined that he wasn't able to go.