Oregon St. Beavers sophomore quarterback Sean Mannion is out indefinitely after a suffering a left knee injury that will require surgery.

The injury occurred during a hand-off in Saturday's 19-6 win over the Washington St. Cougars.

It's a huge blow to the Beavers and one that caught the team off guard. Mannion wasn't on the trainer's report after the game or on Sunday. But a late Sunday night MRI's results came back on Monday with the bad news. Mannion is already in a brace.

Red-shirt junior Cody Vaz will be the new Beavers' quarterback. Though he's been on the active roster every game for the past three seasons, Vaz's only action came in 2010 when he completed 6 of 17 passes for 48 yards in five games. Compare that to Mannion who has 1,358 yards passing with seven touchdowns and four interceptions this season.

The injury couldn't come at a worse time as the Beavers are ranked no. 10 in the Associated Press College Football Poll and still have Oregon and Stanford left on their schedule.