Receiver depth is another.
USC opened training camp with only five sound scholarship receivers.
All-American Marqise Lee, a junior, and sophomore Nelson Agholor are the top two receivers. Senior De'Von Flournoy, sophomore Victor Blackwell and freshman Darreus Rogers will compete for the third spot.
Junior George Farmer and freshman Steven Mitchell are redshirting while recovering from knee surgeries.
The Trojans begin the season Aug. 29 at Hawaii.