"Freshman RB Justin Davis is also out for the season with an ankle injury," the USC athletics blog stated Tuesday evening.
It remains unclear which play during Saturday's game at Notre Dame resulted in the injury to Davis. He was helped off the field at the end of the game by special teams coach John Baxter and a trainer.
"I'm not able to speak on that yet," Orgeron said after practice Tuesday. "It was an ankle...I do know what happened, I'm just not ready to talk about it yet."
Davis left Notre Dame Stadium on crutches wearing a boot on his right leg.
In seven games Davis rushed for 389 yards on 53 carries including a team leading six touchdowns.