Updated

In his first career start, Cody Vaz threw for 332 yards and three touchdowns and the 10th-ranked Oregon State Beavers remained undefeated after downing the BYU Cougars, 42-24, Saturday at LaVell Edwards Stadium.

Vaz, pushed into action because of a left knee injury to starter Sean Mannion, played superbly in his first appearance for the Beavers since 2010, completing 20 of his 32 passes and leading Oregon State to 450 yards of total offense.

"I don't think anybody in our locker room was particularly surprised Cody played well," said Oregon State head coach Mike Riley. "I think they've had faith in him as a teammate for a long time. I knew this was going to be a hard venue to step into, but I thought guys helped him out and made plays."

Markus Wheaton caught five balls for 66 yards with two touchdowns and also ran for another, and Brandin Cooks had a game-high 173 yards on eight catches for Oregon State.

Storm Woods rushed for 57 yards and a touchdown and tight end Colby Prince had one TD catch for Oregon State (5-0), which is now undefeated after five games for the first time since 1939.

Cornerback Jordan Poyer, who had three interceptions last week in a win against Washington State, returned a pick 49 yards for a touchdown late in the fourth quarter to help preserve the Beavers' lead.

Riley Nelson threw for 305 yards with a touchdown and three interceptions for the Cougars (4-3), who have now lost three of five following a 2-0 start. Jamaal Williams carried 15 times for 36 yards and two scores, while Devin Mahina reeled in the Cougars' lone TD pass.

"I thought our offense responded pretty well for the majority of the game, answering scores and I was really glad to see that," said BYU head coach Bronco Mendenhall. "I thought Jamaal Williams emerged and I actually thought we threw it and caught it better than we had and were more consistent offensively probably through three-quarters of the game, maybe three and a half quarters."

Despite two years of not lining up behind center, Vaz looked like a seasoned vet on the game's opening drive. He completed all five of his attempts for 75 yards and linked up with Wheaton for an 11-yard touchdown to put Oregon State up 7-0.

The Cougars roared right back to tie the game, however, with Nelson marching the offense downfield in 10 plays, capped off by a 1-yard TD run by Williams.

After the two teams traded punts, Vaz got back into a groove and put the Beavers back out ahead. He first hit Cooks through the air for a gain of 43 to move the ball down to the BYU 24-yard line, then he capitalized on the next play by throwing a strike to Wheaton for a score.

With BYU threatening at the Oregon State 24-yard line on the next possession, linebacker Rueben Robinson got the ball back for the Beavers by picking off a Nelson pass on 2nd-and-9.

Oregon State was unable to advance past their own 19-yard line, however, and was forced to punt back to the Cougars. JD Falslev returned the ball back across midfield, and a 15-yard penalty on the return by Oregon State set BYU up at the Beavers' 30-yard line.

The Cougars took advantage of the opportunity, with Nelson throwing a 2-yard TD pass to Mahina on 4th-and-goal to tie the score at 14-14 late in the second quarter.

With 6:26 left in the third, Oregon State jumped out to a 21-14 lead. The Beavers put together an 11-play drive, converted a 4th-and-1 just past midfield, and scored three plays later when Woods reeled off a 16-yard run.

BYU tied the game right back at the 2:50 mark, putting together a 75-yard scoring drive in which Williams got his second TD of the day on a 2-yard run.

Vaz, however, kept his composure and marched the Beavers right back 77 yards the other way to put Oregon State back up by a 28-21 score.

After hitting Cooks for a 59-yard gain to put the Beavers at the BYU 5, Vaz took a two-step drop and attempted a quick throw to his left on 3rd-and-goal. The ball was tipped into the air at the line of scrimmage, with Prince snatching it out of the air in the end zone.

A 35-yard field goal by BYU's Justin Sorenson with 8:55 left made it a four- point game, but Wheaton went 12 yards on the ground for a touchdown -- his third of the day -- on a trick play wide-receiver double-reverse at the 5:30 mark, capping a 77-yard scoring drive by the Beavers.

Poyer intercepted Nelson on the Cougars' next possession and took it 49 yards back for a score, making it a 42-24 game with under five minutes left to play.

Game Notes

The series dates back to 1955 and was the 11th overall meeting between the two teams, with Oregon State holding a 6-5 advantage ... Vaz's only other game action for the Beavers came in 2010, when he completed 6-of-17 passes for 48 yards in five outings ... Vaz was 12-of-18 passing for 184 yards and two touchdowns in the first half .., The win gives OSU its first 5-0 start since 1939, when it had victories over Stanford, Idaho, Washington, Washington State and Portland ... The last time the BYU defense allowed over 300 total yards was 2011's 38-28 victory over Oregon State, when the Cougars surrendered 365 to the Beavers.