Justin Davis is USC's only scholarship tailback who can fully participate in spring practice.
Fifth-year senior Tre Madden is expected to be held out of contact drills as he continues to recover from a toe injury that sidelined him last season.
"It allows me to get the reps and perfect my craft going into training camp," said Davis, a junior who backed up Javorius Allen in 2014.
Tailbacks Aca'Cedric Ware, Ronald Jones and Dominic Davis signed letters of intent in February and are set to enroll this summer.
"I've got three hungry tailbacks coming in trying to get my spot," Davis said.
Davis, 6 feet 1 and 195 pounds, played in seven games his freshman season before he was sidelined because of an ankle injury.
Last season, he rushed for 595 yards and four touchdowns, but fumbled four times.