Birmingham skipper Damien Johnson will be out of action for a fortnight after suffering a depressed fracture of the skull.
The Northern Ireland international has undergone surgery after being caught in the face during the first half of Saturday's 1-1 Premier League draw with Fulham.
The midfielder is hoping to be available for the trip to Arsenal on January 12, where he would wear protective headgear.
The injury is the latest in a series of setbacks for Johnson, who missed most of 2007 because of recurring hamstring problems.
Birmingham chief Alex McLeish confirmed: "Damien took a blow and there was a small fracture. But we believe he could be okay for the Arsenal match by using protective gear."