Report: 49ers' Sherman out 2-3 weeks with calf strain

San Francisco 49ers cornerback Richard Sherman suffered a mild calf strain Sunday versus the Kansas City Chiefs and is expected to miss two-to-three weeks, a source told ESPN's Jordan Schultz.

Sherman was helped off the field by trainers at halftime after being unable to put weight on his leg.

The veteran's injury is a blow to a 49ers pass defense that currently ranks 28th in the NFL. Ahkello Witherspoon and Jimmie Ward manned the outside cornerback spots during Sherman's absence against Kansas City.

Sherman, a four-time Pro Bowler, signed a three-year contract with San Francisco after being released by the Seattle Seahawks in March.