Ben Roethlisberger will miss at least four weeks with a knee injury. 

The Pittsburgh Steelers are guarded optimistic that Roethlisberger didn't suffer a torn ACL.

Roethlisberger was seen on crutches following the game, a 12-6 victory, and is scheduled to have an MRI. 

With 5:35 left in the third quarter, Rams safety Mark Barron sacked Roethlisberger after coming on a blitz, hitting him just below his left knee. Roethlisberger went down and immediately grabbed at the knee before the play was whistled dead.

Michael Vick replaced Roethlisberger at quarterback.