Rangers captain Steven Davis could miss the rest of the season after he was told he may need surgery on a groin injury.
The former Aston Villa man limped out of the Glasgow club's SPL clash with St Mirren 10 days ago.
The 27-year-old has definitely been ruled out of this weekend's trip to Hearts, but will see a specialist to determine the severity of the injury.
If surgery is required it would instantly rule him out for the remainder of the season, with the club considering postponing any operation in order for Davis to see through the club's remaining fixtures.
"Davo is struggling a little bit. It's not been confirmed yet in terms of the extent of the injury, but it looks like he'll probably need a wee operation towards the end of the season," Manager Ally McCoist told the club's official website.
"When he gets that done will be decided after a chat with the medical staff, but he won't be involved at the weekend, that's for sure.
"Missing our remaining games is a possibility and that's a concern, but he's going to see a specialist.
"It's certainly calmed down a lot since he came off in the game against St Mirren.
"It's still a niggle for him, but we'll know more once he's seen the specialist."
Should Davis miss the rest of the season McCoist has backed youngster Rhys McCabe to step up.
The 19-year-old only made his senior debut last month but his performances have already earned him a call-up to the Scotland Under-21 squad.
"Rhys obviously played well in the Celtic game and we had him on again when Steven came off against St Mirren," added McCoist.
"We have one or two others who can play in that position, though.
"Maurice Edu has been doing all right and we have other options in there but Rhys would certainly come in to our thinking.
"He hasn't looked out of place at all, and he's a confident lad. He still has miles and miles to go, but he's had a few good games."