Birmingham could give a debut to on-loan Southampton striker Sam Gallagher when Reading visit.
However, recent signing Isaac Vassell could be missing because of a hamstring injury which saw him substituted at half-time in the 2-1 Carabao Cup defeat to Bournemouth on Tuesday.
On-loan Arsenal defender Cohen Bramall suffered a knock against the Cherries and will face a fitness test. Fellow Gunners loanee Carl Jenkinson missed Tuesday's match, but could be in line for his Blues debut.
Birmingham will definitely be without forward Che Adams because of a hamstring injury.
Reading boss Jaap Stam could hand teenage striker Sam Smith another opportunity after his goal helped see off Millwall 3-1 after extra-time in their midweek Carabao Cup tie.
Winger Leandro Bacuna marked his first home appearance with the opening goal and should retain his place, while midfielders Stephen Quinn and Garath McCleary are also hoping to be in contention again.
Liam Kelly (dead leg) and John Swift (hamstring) will be assessed after sustaining injuries in last weekend's defeat at Preston, while midfielder Joey van den Berg is another fitness concern.
Iceland forward Jon Dadi Bodvarsson has been carrying a knee problem, while striker Yann Kermorgant continues to recover from hip and groin surgery.