PROVO -- Cody Vaz passed for 332 yards and three touchdowns in his first start since high school and No. 10 Oregon State used a strong start and bigger finish to beat Brigham Young 42-24 on Saturday.
Vaz was filling in for Sean Mannion, who is out indefinitely with a left knee injury.
Oregon State is 5-0 for the first time since 1939.
Markus Wheaton caught two first-quarter TD passes, and scored on a 12-yard reverse in the fourth, while cornerback Jordan Poyer returned an interception 49 yards to seal the victory against BYU (4-3).
Vaz started 5 of 5 for 75 yards and finished 20 of 32 against BYU's fifth-rated defense.
BYU quarterback Riley Nelson completed 28 of 51 passes for 305 yards and a touchdown, but was intercepted three times.
Oregon State rolled up 450 yards offense.
Brandin Cooks caught eight passes for 173 yards for the Beavers.
Vaz's third TD pass was pure luck as BYU linebacker Kyle Van Noy tipped it at the line. Tight end Colby Prince grabbed it in the end zone for a touchdown while surrounded by three defenders.
It gave Oregon State a 28-21 lead with 14:48 remaining.
A 35-yard field goal by Justin Sorensen pulled BYU within 28-24 with 8:55 left.
That's as close as the Cougars would get.
Vaz directed a 77-yard TD drive, aided by back-to-back pass interference calls against BYU moved the ball to the Cougars' 12. Wheaton then scored on the reverse, with a key block by Vaz, for an 11-point Oregon State lead with 5:30 remaining.
Nelson had BYU moving again, but Poyer's 11th career interception ended the threat.
Both quarterbacks looked as if they were on a mission to quiet skeptics. Vaz completed his first five passes, and by the end of the first quarter, was 8 of 10 for 153 yards with two TDs and a passer rating of 274.5.
Nelson, who had missed the previous two games with what he said were "back fractures," countered Oregon State's first score with a 10-play, 75-yard drive of his own. He showed he was healthy from the start, bootlegging left on BYU's first play from scrimmage and rumbling 16 yards.
He started 5 of 6 for 48 yards, with Jamaal Williams capping the drive with a 1-yard TD run.
Nelson threw his sixth interception of the year at the Oregon State 14-yard line with 8:56 left in the half.
But he made up for it on the next series, directing a 12-play, 30-yard TD drive that saw the Cougars convert three fourth-down plays. The last one was a 2-yard TD pass to tight end Devin Mahina on fourth-and-goal to tie the score at 14 with 3:25 left in the half.
The score was tied at 21 after Jamaal Williams' 2-yard run late in the third quarter.
But with a little bit of luck, Vaz and the Beavers took control.
Wheaton finished with five catches for 66 yards and has now caught a pass in 28 straight games.
BYU counterpart Cody Hoffman finished with 10 receptions for 102 yards, and has now caught a pass in 26 straight games.
Vaz was going against one of the nation's toughest defenses, with the Cougars entering the game 12th against the pass and first against the run (59.3 yards).
BYU's D also had not allowed an opposing offense to score in 13 consecutive quarters. Oregon State took care of that on the first drive.
In the previous three games, the Cougars also had allowed just 10 points combined. Oregon State had 14 just 12 minutes in Saturday, with Vaz picking on cornerback Jordan Johnson early and often.
The Beavers also became the first opponent in the last 13 games to surpass 300 yards total offense. But they didn't convert a third down until 1:20 remained in the third, and converted only 2 of 11 on the game.
It didn't matter.