GARY Waddock is hoping to find out the extent of the injury that has kept Danny Foster out of the pre-season campaign.
The full-back is the only member of Blues' first team squad not to have featured in a pre-season match so far because of the mystery ailment.
Foster is due to have it assessed and Waddock said: "We'll possibly know later on this week whether it's an injury we can get him back quickly from or if it's longer term."
His absence has opened the door for youngster Anthony Stewart, who has featured at right back as well as in the middle of defence.
Waddock has been impressed with his displays and those of fellow teenager Charles Dunne, both of whom excelled against Luton last night.
The Blues boss said: "Both have done extremely well during pre-season and again tonight they have performed very well. They are coming along nicely."
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here