Keeper Brian Murphy will be out for around three months having suffered a broken ankle in training this morning. The 27-year-old was taken to hospital but the injury didn’t require surgery.
Murphy, who joined the Blues a year ago from League of Ireland side Bohemians, has made four league appearances this season, most recently the 1-0 defeat at Preston.
The Irishman has played in all five Carling Cup ties but will now miss the two-legged semi-final with Arsenal and also the FA Cup third round match at Chelsea.
Márton Fülöp returned from his ankle injury to face Leicester at the weekend, while Arran Lee-Barrett will now be on the bench with Ian McLoughlin on standby to come in should another keeper suffer a problem.
Meanwhile, veteran defender Mark Kennedy says his problems with hamstring injuries since joining the Blues in the summer have been frustrating: "One of my biggest disappointments this year is not being able to offer a bit more to the manager and the lads.
"That's something that's been a little bit personal and something I've actually been a bit embarrassed about."
Kennedy has played Town's last two matches and is likely to be at left-back against Watford on Boxing Day.