Rangers defender David Bates faces at least six weeks out with ankle ligament damage.
The 21-year-old centre-back was carried off on a stretcher after going over on his ankle while trying to stop Tom Rogic scoring in his side's 3-2 defeat by Celtic on Sunday.
Gers manager Graeme Murty said: "David Bates suffered a significant injury. He has damaged ligaments in his ankle. He hasn't got a break in there although there is significant bone-bruising.
"I would suggest he is going to be a minimum of six weeks, and whilst it's a difficult one for him to take, and a very, very painful one, I think we should count our blessings because given the mechanisms of it and the freak nature of it, it could have been a lot, lot worse.
"We're devastated for the young man but relieved it's not anything more significant."
Bates has been a key player for Murty since stepping in for the injured Bruno Alves during Rangers' previous meeting with Celtic on December 30.
"He's a young man that kind of encapsulates our journey so far: he has come along way in a short time," Murty said. "There's improvements to be made and areas of development for him, as there are for us as a group and a football club.
"It could be a big loss for us. But it's an opportunity for someone else to continue David's good work and push us forward."
The former Raith Rovers player's future beyond the summer is uncertain but Murty expressed his desire for the player to sign a new contract.
"Talks are ongoing," he said. "We have spoken about his contractual status and his career aims. We just have to keep on reinforcing the positives of being here.
"I think it has been reinforced this week with Bruno, Jason (Cummings), Russell (Martin), Jamie Murphy, Declan (John) all getting into international squads that you can realise some, if not all of your aims at this football club.
"The scale of this football club should never be taken for granted, albeit there is money to be made and opportunities elsewhere, and I have no doubt that people's heads will be turned. But let's not downplay the fact that playing for Rangers, the scale of the club, should not be underestimated by anyone.
"It's a fantastic stage to show your ability, which David has done. But he should never forget that this place here is something special."