Scans have shown that David Murphy's knee injury is not as severe as had initially been feared.
The left back was substituted at half time during last Saturday's 1-1 draw against Burnley at Turf Moor.
The former Hibernian man underwent scans on Monday which confirmed the extent of the problem.
Although Murphy is expected to miss tonight's encounter against Crystal Palace, Alex McLeish says he may even be back in contention for Saturday's home game against Sheffield Wednesday.
"Murphy is not too bad," said the Blues boss.
"We don't believe there is a big problem there but it will probably be enough for him to miss tonight's game, but I don't think it's serious."
In Murphy's second half absence Franck Queudrue stepped into the left back role at Turf Moor and fulfilled the role more than competently according to McLeish and should retain the position this evening
"Franck did okay against Burnley," said McLeish.
"He's been out of it a long time but we've tried to get him to a level where we feel he should be fitness wise.
"At the weekend he showed all his experience when he came in and we believe that he will be able to slot in in place of Murphy and use that fantastic experience and defend well and give us attacking options going forward because the one thing about Franck is his quality on the ball is good in forward areas."
McLeish also revealed that another player has been added to the injury list, with winger Gary McSheffrey picking up a knee injury.
"McSheffrey is out with a knock," confirmed McLeish.
"I know he wasn't in the team before that but he's got a little knee problem.
"Again it isn't that serious but he's out of action whether I decided to bring him back into the action or not."