The 49ers began practice today without two starters, receiver Mario Manningham and cornerback Tarell Brown, and one key reserve, cornerback Chris Culliver.
Manningham (shoulder) and Brown appeared to be sitting out the entire practice; Culliver was in uniform and had his helmet but did not go through any drills. Culliver also has had a shoulder injury; Brown's been on the injury report with a knee injury.
Manningham's injury could provide first-round draft pick A.J. Jenkins with his first snaps of the season. Jenkins has been on the scout team throughout the season; today he was wearing his own jersey.
The 49ers are deep at cornerback. Perrish Cox, who has played in the team's dime packages, is the No. 4 cornerback; Tramaine Brock, who had a prominent role last season, is No. 5.
Meanwhile, outside linebacker Aldon Smith continued to practice in a black, no-contact jersey due to a shoulder injury.
The 49ers will release their first injury report of the week later this afternoon.
- Matt Barrows