Southern California defensive tackle Christian Tupou is likely to miss the upcoming season after tearing a ligament in his left knee during the Trojans' final scrimmage of the spring.
USC learned of the injury's severity Wednesday. Tupou will need surgery.
Tupou has been the Trojans' starting nose tackle for the past two seasons. The injury occurred in the third quarter of the spring game when his knee buckled with nobody touching him.
Tupou made 25 tackles last season, including four for losses. The Trojans are deep at defensive tackle, with Hebron Fangupo set to return from a leg injury and DaJohn Harris impressing new coach Lane Kiffin during spring practices.
Tupou says he plans to use a redshirt season to return in 2011.