Wide receiver Austin Collie suffered a concussion against Pittsburgh, the Colts confirmed Monday.
"He came in today, felt really good, was examined by the doctors and basically is going to be day-to-day," coach Chuck Pagano said. "He felt really good coming out of the game this morning after being evaluated today."
It's remains a concern for Collie, who made it through 2011 after dealing with a history of concussion issues.
Collie was injured when he took a forearm to the helmet from the Steelers' Larry Foote as Collie was being brought to ground after attempting to catch a pass over the middle from Andrew Luck on Saturday. Collie played in 16 games last season, including five starts, and caught 54 passes.
"Again, player safety is first and foremost. We are always going to err on the side of caution," Pagano said.
Defensive linemen Cory Redding (knee) and Robert Mathis (shoulder) also left the Pittsburgh game.
"MRI came back and (Redding's) got a mild MCL sprain. It could be a week or so. We'll see how that thing progresses," Pagano said. "Mathis is fine. We had a bunch of guys with nicks and bruises but basically those (Collie and Redding) are the two major ones."