USF sophomore receiver Sterling Griffin, expected to contend for a starting role this fall, injured his ankle during voluntary workouts on campus Monday.

The severity of the injury isn't known, but an ambulance was called to the practice fields east of USF's athletic facility, and Griffin was taken to the hospital for X-rays. Tampa Fire Rescue confirmed that an ambulance responded at 9:20 a.m. to a call about a sprained ankle.

Monday marked the first day of classes for the Summer B semester and the first day of college classes for most Bulls newcomers. During summer classes, players have their own informal workouts without pads on -- position coaches cannot supervise workouts until the start of fall practice the first week in August.

Griffin had 14 catches for 265 yards and two touchdowns as a true freshman last fall and is expected to play a larger role this season at a position where USF lacks significant experience. The Bulls lost rising senior Carlton Mitchell to the NFL draft, and another senior starter, A.J. Love, is recovering from a knee injury sustained in USF's spring game. Senior Dontavia Bogan, who dominated in the spring game, is an established starter, but the rest of the group is largely unproven.

Some of the help expected to arrive this fall has been held up, as freshman receiver Jamaal Montague was not among the newcomers reporting last week to start summer classes. Montague said Sunday that his final coursework from high school was coming in late, but that he was "pretty sure everything is going to work out" for him to join the Bulls for two-a-day practices in August.

Times correspondent Kerry Klecic contributed to this report.