Steelers' Ryan Clark out with concussion

PITTSBURGH -- Steelers safety Ryan Clark is out of Sunday's game against the Redskins with a concussion.

Clark took a shot to the head on a tackle in the third quarter. He walked off the field on his own and then went to the locker room for evaluation.

The Steelers are now without their two starting safeties, Clark and Troy Polamalu (calf). Ryan Mundy has joined Will Allen as the Steelers' safeties.

Pittsburgh is up on the Redskins 27-9 with 5:13 left in the third quarter.