Oregon State head coach Mike Riley addressed the media after Monday's practice and announced that quarterback Sean Mannion would undergo knee surgery, according to a USAToday report by Gary Horowitz.
The report states that Riley said Mannion would be out for "an undetermined amount of time" after Mannion's MRI tests came in Monday.
Riley, according to the report, has tabbed redshirt junior Cody Vaz as the starting quarterback against BYU on Saturday.
"We're gonna win the game with Cody," Riley said. "Cody is a good quarterback and he's been preparing for this for a long time, so he'll be good and we'll be ready to go."
Mannion is currently the sixth-most productive passer in the nation and has a 139.75 passer rating. Vaz has attempted a career total of 17 passes and completed six of them, the last one against Oregon almost two years ago.
The Beavers are currently ranked No. 10 in the AP and travel to Provo, Utah for a Saturday game against BYU.