Nikica Jelavic is unlikely to face Swansea at the Liberty Stadium on Saturday, according to manager David Moyes.
The Croatian striker suffered a series of blows during the first half against Newcastle United on Monday night.
The most serious of those came in just the second minute as he collided with the post, badly bruising his knee and shin.
Darron Gibson (thigh) is already out, while Moyes also said Tony Hibbert could be struggling.
The Blues boss said: “We have got a doubt about Tony Hibbert and I don’t think Nikica Jelavic will be fit for this game.
“They will be misses but we have got quite a good squad so hopefully we will be able to deal with it.
"Darron was missing for the game against Newcastle but I didn't think it was that obvious in the team performance.
"I thought the team played really well. It wasn't his miss that meant we didn't win the game or get maximum points. But he has done really well for us."