The 49ers played most of the first half without the left side of their starting offensive line after Joe Staley left with a right knee injury. San Francisco has surrendered four sacks, but thanks to another strong defensive effort and a slew of penalties against the Rams, they lead 13-3 at halftime.
Receiver Michael Crabtree played most of the first half and has one catch for eight yards. Colin Kaepernick's favorite target remains Anquan Boldin, who has six catches for 67 yards. Kaepernick has targeted Boldin five times on third down; each has resulted in a first down, two by penalty. The Rams have been penalized seven times for 60 yards. San Francisco has six penalties for 60 yards.
With Staley out, Alex Boone has shifted to left tackle. His main opponent, Robert Quinn, has no sacks and one tackle through 30 minutes of play. Joe Looney stepped in at right guard -- Boone's former position -- and played well, at least until being penalized for holding on the final drive. He was replaced just before the half with Daniel Kilgore.
- Matt Barrows