Roque Santa Cruz faces at least a month on the sidelines with the calf injury that flared up against Everton.
The striker was forced off the field with just eight minutes of last Saturday's game gone when the problem that kept him out of action over the Christmas period recurred.
Speaking to mcfc.co.uk on Monday lunchtime, Blues boss Roberto Mancini confirmed that he will have to do without the Paraguayan for a number of weeks.
"It looks like a bad injury for Roque, it is to the same calf that was a problem around Christmas. It could be around one month, we don't know exactly when he'll be back yet. It does not require surgery, just treatment."
...Mancini on Santa Cruz...
One player Mancini will be able to call on for Tuesday night's Carling Cup semi-final derby is Stephen Ireland. The midfielder has been absent since he strained a hamstring at Molineux three weeks ago, but the manager is confident that he is available for selection.
"Stephen is ready," he declared. "He trained with the team yesterday (Sunday) and will do again today. He is not ready to play a whole game, but it's certainly possible that he can be on the bench."
However, Mancini will not be taking a risk on Patrick Vieira, whose own calf injury, a legacy of his final game for Inter Milan, has so far prevented him from making his City debut.
Mancini said: "It's better for us and for him if he can be ready to play in another week or ten days. It's better that we don't risk his situation because I would prefer that when Patrick comes back, he can play to the end of the season.
"I would want him to be ready to play 20 games, I would prefer him to come back after the next game or for the return match against United."
Wayne Bridge and Joleon Lescott are reported to be making good progress from the knee injuries that have sidelined them since last month, but again the manager is wary about rushing them back with an eye on the run-in at the latter part of the season.
He said: "I'll wait for them, because they are important players for us. I hope that Bridge can come back in ten days - with Joleon, I hope around another ten days on top of that. They are making good progress but are not ready to train."