Tailback Justin Davis has sat out four of USC's first five practices because of a hamstring injury, providing opportunities for freshmen Ronald Jones II, Dominic Davis and Aca'Cedric Ware.
All appear capable of contributing in their first seasons.
The trio performed well again during Wednesday's full-pads workout before Thursday's day off.
Coach Steve Sarkisian described Jones as "an electric, speed guy."
Dominic Davis is a "do-it-all guy," who will play from the backfield and the slot, running backs coach Johnny Nansen said.
Ware had his best day Wednesday.