BLUES captain Chris Barker was forced to hobble off during the first half of Saturday's 2-1 win at Wycombe Wanderers with an Achilles problem.
The experienced defender had missed three games with a calf strain before returning to face Leyton Orient last Wednesday.
But Barker has now picked up another injury.
“Chris has a different injury to the one he had before and that's why he had to come off,” said Blues boss Paul Sturrock.
“It was obviously a disappointment but we will assess him today and find out how serious the injury is and we will then have more idea about how long he will be out for.”