Bradford captain David Wetherall will be out of action until the New Year after tests revealed complications with his knee problem.
Wetherall joined Bradford from Leeds in 1999 for £1.4m
The experienced centre-back had initially been expected to spend a month on the sidelines after sustaining the injury during last week's 1-0 defeat at Watford.
But club surgeon Steve Bollen has predicted an absence of three months after confirming medial ligament damage.
Wetherall will wear a brace to support his left knee for the next five weeks.
"I am absolutely gutted because I was feeling really good. I was feeling fit and strong and playing well," said Wetherall.
"I had got a full pre-season in me and in the last six or seven games really started to get on top of the centre forwards I was up against. It is massively disappointing that this has happened.
"But I can't do a thing about it. I have just got to rest it up for the next month and then it will be a case of effctively doing another pre-season.
"In the meantime I just hope that the rest of the lads can do well and get us out of the position we are in," he told the Bradford Telegraph & Argus newspaper.