Southern California receiver Marqise Lee left practice early Friday after apparently injuring his right shoulder.
The All-American appeared to get hurt while attempting to catch a long pass from Cody Kessler in coverage. He stayed down on the field before USC's medical staff escorted him away.
Coach Lane Kiffin provided no update on Lee's condition after practice, saying he hadn't seen exactly what happened to his top player.
Kessler says Lee told his teammates he would be "fine" before he left the field.
Lee had 118 receptions for 1,721 yards and 14 touchdowns last year as a sophomore, winning the Biletnikoff Award as the nation's top receiver. He also was the Pac-12's offensive player of the year.
Lee also is a dynamic kick returner.