Blues youngster Jack Lankester will miss the next few weeks with a back injury, while midfielder Emyr Huws has suffered a setback as he continues his return from more than a year out.
Speaking at his lunchtime press conference, manager Paul Lambert revealed Lankester, 18, would be out for the next few matches.
"Everybody’s not too bad, but young Jack’s going to be out for a number of weeks, which is a blow. But everybody else is OK,” he said.
"Jack’s got a problem with his back at the minute so we’ll just have to manage him through that.
"Obviously, the load has been a helluva a lot for him to take on at 18 years of age. A year ago I think he was out on loan at Bury Town and the rise for him as been dramatic. But he’s going to be a player, he’s going to be a right top player.
"It’s just been a build-up of stress, the demands of it. It can be a common thing for a young player with the load. But he’ll be back and he’s going to be a really good footballer.”
Huws has yet to play since suffering a knee injury at Middlesbrough at the start of December 2017, but was on the bench for the Rotherham match but dropped out of the party which travelled to Blackburn last week due to a calf problem.
"He’s had a little setback,” Lambert confirmed. "It’s not as bad but it’s a little setback, so we’ll just have to nurture him through it, which is a blow because I think Emyr’s got a really good footballer in there but the big challenge for him is to try and stay fit. He’s not [in contention for this weekend], he’s not ready for it.”
The Town manager says he hopes the Wales international will be back at some stage in the remaining months of the season.
"I would hope so, that's the plan to get the lad back playing games,” he added. "It’s frustrating for him. It really must be a nightmare for him having to go through this every so often. For his own sake, I think it’s important mentally to try and get him back playing.”
Another midfielder Tom Adeyemi is yet to feature since pre-season due to an achilles injury which eventually underwent surgery having missed most of the previous campaign with a hamstring problem.
"Tom’s another one, he’s doing OK,” Lambert continued. "He’s been out for over 14 or 15 months, a helluva long time [out] these lads here have had with injuries.
"As I said before, mentally it’s no good for them. We’ll just have to wait and see how his injury gets on but he’s doing OK.”
Grant Ward is out for the season having suffered rupturing his anterior cruciate ligament at QPR on Boxing Day.