The 4-0 Oregon State Beavers will be without starting quarterback Sean Mannion for an undisclosed amount of time, as he will have surgery on his knee, reported Stephen Nelson of KEZI 9 Sports. Mannion will be out for an undisclosed amount of time, according to Oregon State head coach Mike Riley.

Oregon State has started the season 4-0, winning its first three conference games to climb up to No. 10 in the AP Top 25 Week 6 rankings.

The sophomore Mannion is completing 63.3 percent of his passes and has thrown seven touchdowns to just four interceptions through four games this season. Three of those interceptions came against Washington State last Saturday when Mannion had his worst game of the season, but the Beavers still escaped with a 19-6 win.

Oregon State will play its first game without Mannion this Saturday when they travel to face the BYU Cougars. The game against BYU will be the Beavers' third road game in four weeks, as they defeated UCLA and Arizona on the road in Weeks 3 and 4.

This story originally appeared on SBNation.com.