Striker Adam Proudlock suffered a recurrence of his knee problem during last night's 2-0 reserves defeat at Southampton. The former Sheffield Wednesday man was replaced by youngster Kieran Leabon at half-time.
Proudlock's problem is not thought to be too serious and he could still be in contention for a place on the bench at Preston on Saturday.
Town have three of the regular back four currently out of training. Fabian Wilnis is considered a doubt after hurting his knee in his first half collision with Richard Naylor in Saturday's game with Leicester.
Naylor himself is also being rested, while Jason De Vos has an arthritic toe, but both Town's centre-halves are expected to be OK for the trip to Deepdale.
The Blues continue to be hopeful that Alan Lee will be fit enough to play after his hamstring injury. The Irishman is expected to be back in full training on Thursday.