The Steelers have placed rookie CB Curtis Brown on injured reserve because of a knee injury.
The team's third-round pick last April, Brown made an instant impact on special teams, leading the Steelers in special-teams tackles with 15.
Taking his place on the roster will be RB John Clay, who was signed from the practice squad. An undrafted rookie from Wisconsin, Clay will be the team's third-string runner this week against the Rams behind Rashard Mendenhall and Isaac Redman. The team's regular No. 3 back, Mewelde Moore, is out with a sprained MCL.