Manningham active vs. depleted secondary

SEATTLE -- The Seattle Seahawks had hoped to have cornerbacks Walter Thurmond or Marcus Trufant available to face the San Francisco 49ers on Sunday night.

Neither is active.

The 49ers, meanwhile, are getting receiver Mario Manningham back from a shoulder injury. San Francisco could be in better position to attack the Seahawks with three-receiver personnel groupings. However, the 49ers seem to be most comfortable using two backs and/or two tight ends.

How much will they change to exploit a potential matchup advantage?

The 49ers rank last in the NFL this season in yards per game while using three-plus wide receivers on first and second down, according to ESPN Stats & Information. That doesn't necessarily mean the 49ers are weak in that area. It mostly means they don't use that personnel much on early downs.

Seattle will have top cornerback Richard Sherman for this game while Sherman awaits word on his appeal of a four-game suspension for allegedly using performance-enhancing drugs. Backup corners Jeremy Lane and Byron Maxwell have shown promise as well, but they remain unproven.