Left-sided duo Dan Harding and Matt Richards are doubts ahead of Saturday's trip to Luton. Both players limped off during Tuesday's game at Preston after challenges from loanee Lilywhites midfielder Franck Songo'o.
Harding, like Richards, has an ankle problem, despite initial reports that he had injured his knee during the second half of Town's 1-0 defeat at Deepdale.
Town's head of sports science Dave Williams told the club site that he expects Harding to be fit: "Both players have sprained ankles and are having treatment.
"We're hopeful that Dan will be OK and of the two Matt is the bigger concern. We will have another look at them on Friday and take it from there."
The Blues will have Alan Lee available after suspension for the visit to Kenilworth Road.