Bailey was injured Wednesday. He suffered what Coach Lane Kiffin described Thursday as a hip injury.
Kiffin said Bailey "should be back pretty soon" and that "it's not as bad as it looks."
It certainly doesn't look good for USC's secondary with the Aug. 29 opener against Hawaii coming up in less than two weeks.
Bailey provides play-making ability and leadership for a secondary that is still searching for starting cornerbacks.
"Guys still have ups and downs, and flash and get beat, so it really hasn't shown itself yet," Kiffin said, adding that Friday's scrimmage "will be big."