Steelers coach Mike Tomlin revealed in his press conference Tuesday RB Mewelde Moore sprained an MCL in Pittsburgh's 20-3 loss in San Francisco Monday.
His status for Saturday's home game against St. Louis is questionable.
The Observer-Reporter's Doug Lolley speculated via Twitter if Moore cannot play, the Steelers may activate rookie John Clay from the practice squad. Jonathan Dwyer, the former third running back on the depth chart, was placed on Injured Reserve last week.
Starting RB Rashard Mendenhall has bruised ribs, but is expected to play Saturday, after a short week of recovery.
Tomlin also said OLB LaMarr Woodley didn't injure his hamstring during the game, but it was "fatigued," which was the reason Woodley was absent toward the end of the game. He is expected to play Saturday.
He addressed the elephant in the room - QB Ben Roethlisberger's health and Tomlin's reason for keeping him in the game - simply by saying there were "no issues concerning pulling him at any point in terms of health. I'm not going to deny those guys the opportunities. That's how we're built."
He did, however, comment non-verbally on his opinion of the officiating by saying he did not get a very good explanation from the official as to why LB Lawrence Timmons was flagged for "leaping" during a David Akers field goal attempt.
The penalty gave the 49ers a first down, and they eventually scored the final touchdown of the game.
The injuries are the story this week, however. With so little time to prepare, and Tomlin and the Steelers likely having stepped off the plane from San Francisco around 7 a.m. ET Tuesday, they will have to make personnel decisions quickly. St. Louis may not be the league's best team (to put it mildly), but with the Steelers so far out of their standard routine, focus and health are paramount in the little time they have to prepare.