Bristol City have discovered Louis Carey has sustained a muscle tear and face being without their skipper for an extended period.
The experienced defender took a kick on the calf during the defeat by Leeds on 13th November and was expected to return to action against Derby this weekend.
But after suffering further discomfort during a training session an ultrasound scan revealed a much more serious injury than first feared.
Robins boss Keith Millen has confirmed his skipper will not feature against the Rams and remains unsure as to when he will be back in action.
"Louis has no chance for the Derby game and I'm not even considering him," Millen told the Bristol Evening Post.
"He did a training session the Monday before last and complained of discomfort in his calf after he had finished.
"We sent him to hospital for a scan as a precaution and were surprised when it showed up a tear in the muscle.
"Having thought he would be out for two to three weeks, we've now had to revise the date for his comeback."