Captain Mark Hudson and striker Rudy Gestede could both return to Cardiff's matchday squad.
The duo have missed the Bluebirds' last three outings, including the 2-0 Carling Cup quarter-final victory over Blackburn in midweek, with hamstring problems.
Should the pair be available, however, manager Malky Mackay would be presented with a selection headache.
Hudson's replacement in the Cardiff starting XI, Anthony Gerrard, scored in the win against Blackburn, while Gestede would have to oust Kenny Miller, who also netted against Rovers.
Otherwise, Mackay does not have any new injury or suspension worries as his team look to extend their unbeaten streak in all competitions to 10 matches.
Goalkeeper David Marshall could be in line for a return in between the sticks, however, after the stopper lost his place to Tom Heaton for the Carling Cup tie on Tuesday.
Birmingham duo Stephen Carr and Liam Ridgewell will both be assessed.
Right-back Carr was rested for City's midweek Europa League defeat to Braga in Portugal due to a sore knee while left-back Ridgewell continued to miss out due to his thigh problem.
Carr stands a good chance of returning into contention in the Welsh capital but even if Ridgewell passes a fitness test he is unlikely to dislodge David Murphy.
Morgaro Gomis returned to the bench at Estadio Municipal de Braga following his calf injury and will hope to feature against Cardiff, but the game comes just too soon for returning midfielder Jordon Mutch (broken ankle).
Manager Chris Hughton will continue to shuffle his pack to cope with the demands of Europe and the club's promotion campaign, with the likes of Marlon King and Chris Wood in contention to come back in.
City's squad do, however, have an extra 24 hours to recover with the tie against Braga taking place on Wednesday this week and not the usual Thursday slot for Europa League encounters.
