USC tailback Silas Redd has been ruled out for the Trojans' game Saturday against Stanford due to a right knee injury.
USC's Marqise Lee, the 2012 Biletnikoff Award winner as the nation's top receiver, left the Trojans' practice early on Friday after suffering an apparent injury.
USC freshman wide receiver Steven Mitchell will miss the 2013 season after suffering torn ligaments in his right knee during a voluntary workout on Friday morning.
USC Trojans tight end Xavier Grimble will miss the remainder of spring practices because of a chest fracture, according to Trojans coach Lane Kiffin.
Injuries have caused the USC coaches to get creative with the starting lineup going into tonight's game at Colorado.