The champions are in genuine trouble. After a dominant start to the season, two defeats in three league games have exposed the lack of depth running through a Chelsea squad that is one of the smallest in the league.
In years gone by a defeat such as the one suffered against Sunderland last weekend would have resulted in a backlash, and you could be sure that the Blues would get right back on their feet.
At the moment, however, there are simply no extra players available to Carlo Ancelotti were he to want to change his side around. The same team that collapsed against the Black Cats may well have to start this fixture. Alex and John Terry look set to be out until the New Year and with only one centre back possessing any experience in the Chelsea squad, Birmingham could have a field day, as they welcome a team to St Andrews that failed to score here last season.
Birmingham have not been in vintage form themselves, however, will have been boosted by their ability to keep Manchester City at bay for 90 minutes away from home, and with Chelsea missing at least four crucial players, a draw here may even be considered a good result for the current league leaders.