Mario Manningham done for season for San Francisco 49ers

San Francisco 49ers wide receiver Mario Manningham is done for the season after tearing the ACL and PCL in his left knee during Sunday night's 42-13 loss to the Seattle Seahawks, a source who has spoken with the player told NFL.com's Albert Breer.

Manningham had an MRI on Monday after X-rays on his knee were negative.

Manningham ranks third on the 49ers with 449 receiving yards on the season. The fifth-year pro out of Michigan missed two games earlier this month because of a shoulder injury.

He wasn't the only 49ers player to suffer a significant injury Sunday.

Pro Bowl tight end Vernon Davis suffered a concussion and must follow the NFL's concussion protocol before being cleared to play in the 49ers' regular-season finale against the Arizona Cardinals.