Eugene, OR -- (Sports Network) - Oregon sophomore quarterback Nate Costa will likely miss the entire 2008 season after again undergoing surgery on his left knee.

Costa, who missed the 2007 campaign with an injury in the same knee, underwent surgery to repair a partially torn anterior cruciate ligament and cartilage damage on Wednesday. He injured the knee in practice on August 20. Costa was expected to start for the Ducks this season, but instead sophomore Justin Roper will be the signal-caller.

The Ducks are coming off an injury-marred 2007 season. Oregon reached No. 2 in the AP poll after an 8-1 start that included wins over Michigan, USC, and Arizona State, but lost star quarterback Dennis Dixon to a torn ACL in his left knee early in a loss at Arizona on November 15. The Ducks saw their Pac-10 and BCS title chances fade with a subsequent three-game losing streak.

Oregon, which finished 9-4 in 2007, opens this season at home against Washington on Saturday night.