Harrison, who apparently hurt his knee against the Detroit Lions on Sunday, "actually has a hamstring issue," coach Tony Dungy said Wednesday.
The availability of running back Joseph Addai and safety Bob Sanders will likely be game-time decisions, Dungy said.
"I'd say he's questionable at this point. We'll have to see," Dungy said. "And, obviously, we're going to be cautious if there's any issues at all, as we will with Joseph and Bob."
Addai has been nursing a sore shoulder, which he injured Dec. 7 against the Cincinnati Bengals, and did not play Sunday against Detroit. Sanders, whose right knee was swollen last month, was also held out of the Lions game.
He said both players have practiced with the team this week and want to play.
"They're excited about going. My sense is they'll play, but we'll see what happens," Dungy said. "We probably won't know until game time. It's going to be one of those things we'll probably have to wait and see."
Paul Kuharsky covers the NFL for ESPN.com. Information from The Associated Press was used in this report.