INDIANAPOLIS (AP) -San Francisco left tackle Joe Staley sprained his right knee on the first play Sunday against the Colts, and his return was doubtful.

Staley has started every game of his three-year career. Barry Sims stepped in for him.

The 49ers already have lost right tackle Tony Pashos for the season with a broken left shoulder blade. Pashos was hurt during last week's 24-21 loss at Houston.

San Francisco coach Mike Singletary has called the offensive line his biggest area of concern.