Rangers expect on-loan defender Kyle Bartley to be sidelined for five or six weeks but are not sure whether he will require surgery.
Bartley, who returned to Ibrox on a season-long deal from Arsenal over the summer, broke down with what was thought to be a groin problem during the 2-0 win at Inverness last month.
Doctors have now diagnosed a hernia which may force Bartley to go under the knife, with Rangers not anticipating that he will be able to return to action until mid-October.
"Kyle has a hernia problem and we expect him to be out of action for between five and six weeks, although I'm not sure at this stage if surgery will be required," director of football Gordon Smith said in the Daily Record.
"Either way, it's obviously a big blow for the boy and the club."
Bartley joined Rangers on loan for the second half of last season but had to be sent back to the Emirates Stadium after making only eight appearances because of knee ligament damage.
Wallace eyes return
In more positive injury news for the club, Lee Wallace is hoping to be available for the Old Firm date at Ibrox on 18th September following a hamstring problem.
"It has been frustrating to be out recently but these things happen," the full-back told the club's official website.
"I'm working hard with the physios and I'm aiming to be back as soon as possible but I've just had to be a bit careful after being out for a long while last season.
"The Celtic game is a huge one for the club and that's certainly one I'd look to be involved in if I can be.
"When you come to a club like this, that's the type of match you want to take part in. It's massive for both sides and when you win it's just great.
"I want to be a part of it all and although it has been tough for the manager with the bad luck we've had lately with injuries, I hope to be back for that one.
"We're all racing to be back fit again and my personal aim is probably to return in time for the Old Firm game. I just need to work hard and get back for that."