Blackburn manager Henning Berg will give Jason Lowe, Gael Givet and Colin Kazim-Richards every chance to prove their fitness to face Birmingham.
Defender Givet pulled up with a leg injury in training on the eve of last weekend's 2-0 defeat at Crystal Palace, Berg's first game in charge, while forward Kazim-Richards suffered a muscle strain during Tuesday night's 2-2 draw at Huddersfield.
Lowe went off in the closing stages of the 1-0 win over Watford at Ewood Park a fortnight ago and is battling to return from a hamstring problem.
Veteran forward Nuno Gomes (knee) remains a doubt and midfielder David Dunn (calf) is expected to remain on the sidelines despite stepping up his recovery work in the gym.
Teenage right-back Adam Henley has been preferred to Bradley Orr since Berg's arrival and is set to continue.
Portugal U21 winger Fabio Nunes is still out with a hamstring injury.
Birmingham trio Curtis Davies, Nathan Redmond and Leroy Lita are all rated as 50/50 for the trip.
Centre-back Davies hobbled out of Tuesday's 2-0 win over Bristol City just before half-time due to the troublesome ankle injury he first sustained in the home defeat to Huddersfield.
Winger Redmond (dead leg) and on-loan striker Lita (thigh) both missed the clash altogether, and all three face a race against time to be fit for the Ewood Park showdown.
Defender Pablo Ibanez played 70 minutes for City's Development squad on Wednesday afternoon and is set to come back into the matchday squad.
Paul Caddis is making excellent progress in his recovery from his shoulder injury and is not too far away, but fellow right-back Stephen Carr (knee) remains a long-term absentee.