Lions QB Matthew Stafford will be a game-time decision for Sunday's game vs. Pittsburgh with a right knee injury.

"We'll definitely announce it Sunday, because there is a lot of time between now and Sunday," Lions head coach Jim Schwartz said Friday.

Stafford was limited in on practice on Friday after sitting out Wednesday and Thursday. The 21-year-old rookie has picked up his play in recent weeks and threw for a season-high 294 yards at Chicago in Week Four.

If Stafford can't go, the Lions will start Daunte Culpepper in his place.