What will be Mario Manningham's impact?

SANTA CLARA, Calif. -- The San Francisco 49ers are set to get some much-needed relief at receiver.

Mario Manningham is expected to start practicing this week. The team will have three weeks to activate Manningham. He has been out all season with a knee injury he suffered last December.

The 49ers badly need more production from their receivers. Their only true passing-game weapons this season have been Anquan Boldin and tight end Vernon Davis. The team also hopes to get standout Michael Crabtree back from a torn Achilles, perhaps as early as Mid-November.

Manningham will get the first chance to help the 49ers. The 2012 free-agent addition had 42 catches for 449 yards in 12 games last season. Especially with Crabtree still out, expect Manningham to be a top option for the 49ers when he returns.

ESPN’s Matt Williamson said he doesn’t think Manningham is a top option, but he will give some life to this receiving crew when he returns.

“He is certainly an upgrade over what the Niners have been using as a No. 3 option in the passing game,” Williamson said. “He has big-play ability and at least some sort of pedigree of NFL success. He sure can’t hurt.”