Celtic will be without Beram Kayal for the rest of the season after the midfielder underwent ankle surgery.
Kayal was injured during the Old Firm win on December 28 - he hurt his ankle in a challenge with Lee McCulloch - but the club had hoped that he would be able to return in a matter of weeks.
However, scans revealed he suffered cartilage and ligament damage and as a result surgery was recommended, bringing his season to a premature end.
"Beram Kayal underwent surgery last night on his injured ankle and the club can confirm that, unfortunately, our worst fears have been realised and Beram will be out of action for at least four months," the club confirmed in a statement.
Manager Neil Lennon admits the news is a blow for the club given his impressive performances to date.
"This is very sad news for Beram. He has been brilliant for us and instrumental in our performances during the season," Lennon said.
"He will definitely be a big loss for us, but more importantly we are disappointed for him to be missing such a large part of the season at a time when he was playing so well.
"Clearly his health and fitness is now our priority and we will be making sure he gets our total support during the coming period."