Rangers expect to be without Scotland international midfielder Graham Dorrans for around three months after he was forced to undergo surgery on an ankle problem.
The 30-year-old scored five goals in the league appearances for the Gers following his summer arrival from Norwich City, but he has been sidelined since a 1-1 Ibrox draw with Kilmarnock in late October.
We are looking at him being out for 12 weeks.Graeme Murty
The Glasgow giants had hoped that rest and recuperation would ensure that an operation was not necessary, but caretaker boss Graeme Murty has confirmed that his players has now had to go under the knife.
He told the club's official website: "We took him to see a specialist who recommended a conservative approach, so we followed that for a couple of weeks and unfortunately it didn't take.
"It is a sore one for him to take, but we believe we did the right thing by trying to be conservative and getting him back without the surgical option.
"We now move forward with an extended rehab programme for him. We are looking at him being out for 12 weeks."
Rangers play host to St Johnstone on Saturday, having enjoyed victories in each of their last four Scottish Premiership games.
Striker Alfredo Morelos has found the net in his last two appearances, having gone ten games without a goal after notching eight in his first nine outings for the Gers.
Rangers are 1/1 to make it five wins in a row, with Morelos 1/1 to score any time for the hosts, who are 1/1 to claim a 2-0 victory.
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