Rangers goalkeeper Stefan Klos has been ruled out for at least the rest of the season after picking up a cruciate ligament injury in training.
Stefan Klos is an important player for Rangers
It is a severe blow for Rangers as Klos is not only their captain but has been in excellent form this season.
Rangers manager Alex McLeish admitted Klos' absence was a massive disappointment to the club.
"But it doesn't mean that, because we have lost Stefan, we can't win the league," he added.
"Stefan is a fantastic goalkeeper, but we have lost him to injury and we have to be positive and look forward.
"With young Allan McGregor coming into the team, we have to ensure he is not a loss.
"Obviously it is a blow for Rangers Football Club. I am really disappointed for Stefan because we tend to think of him as Superman, who doesn't get injured.
"I will only be able to tell you how big a blow it is at the end of the season if we don't win the title."
Klos was hurt when his studs caught on the Murray Park turf as he attempted to make a save.
McLeish said: "A striker went through on a one-on-one situation and Stefan planted his feet on the ground.
"When the striker changed the direction of the ball, he tried to turn and his studs caught in the turf.
"It was a totally innocuous training ground incident but one that I have seen many times causing this type of injury."
Klos has travelled to Germany to see a specialist and undergo surgery.
McLeish insisted he would not rush to bring in a replacement for Klos before Monday's closure of the January transfer window.
It is likely Rangers would be allowed to sign another keeper outwith the transfer window as the rules governing the signing of goalkeepers in "emergency" situations are less strict.
"Allan McGregor has been very patient and he thought he was coming back from St Johnstone to see out the season on the bench," added McLeish.
"But I told him I was delighted with what I saw of him at St Johnstone, where he had six shut-outs in a row, and that, if anything should happen to Stefan, I would have no doubts about putting him in."
McGregor has made only seven starts for Rangers.
Graeme Smith remained at Ibrox as cover for Klos, but the 21-year-old has yet to make a single first-team appearance.
He had been told that he would not be offered a new contract at the end of the season and had been on trial with Dundee United.
Klos was recently linked with a move to Arsenal but made it clear that he wished to remain at Rangers for the rest of his career.