USC receiver Marqise Lee was returning a punt when he went down and took an extended period of time to get up.
His Trojan teammates huddled around him as he laid on the field tended to by trainers.
Teammates eventually helped Lee off the field. He was then examined by trainers on the sideline before being taken by a cart back to the locker room.
After the game USC head coach Lane Kiffin said he did not have any update on the status of Lee, who suffered an apparent knee injury.
"It didn't look very good," Kiffin said in his postgame press conference. "It didn't sound very good or look very good. So that's all I got for you."
USC tight end Xavier Grimble said that Lee's tests came back "positive" and that he should be "okay".
Lee left the stadium on crutches.
He finished with seven catches for 92 yards, including a 51 yard long.