The Croatian marksman has been a massive flop at Villa Park up to now, and spent last season back home on loan at Dinamo Zagreb.
The arrival of new boss David O'Leary had given Balaban a ray of hope in his fight to make it in the Premiership, but that has now suffered a new blow.
Former Leeds boss O'Leary has promised a fresh start at the club and was willing to give everyone a chance to earn a place in his starting XI.
Balaban limped out of a training session after he turned over his ankle and he is now a doubt for the club's pre-season tour of Scandinavia.
Balaban will be desperate to get fit for the trip as it is his chance to make an impression on O'Leary.
