San Francisco 49ers cornerback Chris Culliver will miss the season with a torn ACL in his left knee.
Culliver was injured Thursday during a non-contact drill. Defensive coordinator Vic Fangio said Friday that the loss of the third-year veteran "puts stress" on a cornerback group that faltered late last season and in the playoffs during San Francisco's run to the Super Bowl.
The 49ers brought in four-time All-Pro Nnamdi Asomugha in April to augment the position behind starters Carlos Rogers and Tarell Brown. The team returned its top five cornerbacks from last season.
Culliver was San Francisco's third cornerback the past two seasons and played a key role in the team's coverage packages, often taking over at left cornerback when the 49ers went to their nickel defense.