The midfielder was carried off on a stretcher after suffering damage to a knee in a challenge from Cedric Kipre during Rangers’ 2-0 win over Motherwell at Ibrox.
Murty, whose options in that area of the pitch are already limited by a long-term injury to Graham Dorrans, does not expect Jack to be available this weekend.
“Ryan is in a bit of pain and discomfort,” said Murty. “His leg is in a brace at the moment and we will assess him tomorrow. I would imagine he would be a doubt, looking at the manner of the injury and his departure from the pitch.
“But he’s a hardy guy and if there’s any chance of him being involved, I’m sure he will be desperate to make the team.”
Murty was unwilling to pass comment on Kipre’s challenge on a night which also saw Rangers striker Eduardo Herrera suffer a bloodied nose following a boot in the face from the Motherwell defender.
“I’m going to plead ignorance and say I followed the line of the ball,” added Murty. “I’ve got no doubt I’ll get plenty of different clips of it from different angles. I’ll have a look at it when I get the chance. But at the moment I’m more concerned with how Ryan is than anything else.
“Eduardo took one in the face. The ball was quite low and the centre-half decided to go for it. It was a footballing incident. Eduardo has a bloody nose and is in a bit of pain but sometimes as a centre forward, these things happen. The referee dealt with it and we move on.
“We accepted what was coming, there wasn’t any petulance from us. We stood up to it and got a good result.”
Murty took encouragement from the manner of his team’s response after losing their two previous games against St Johnstone and Kilmarnock as they now prepare to face champions Celtic.
“It gives me hope the guys can meet the challenge,” he said. “They stood up to a really physical challenge tonight. It will be a different challenge on Saturday, a technical and tactical one. They have to show a mentality and desire to represent the shirt and make the fans proud.”
Motherwell manager Stephen Robinson bemoaned his team’s failure to convert a couple of clear-cut opportunities while the game was still goalless and admits he needs to perform major surgery on his squad in next month’s transfer window.
“If you don’t take your chances when you come to Ibrox, then you’re going to lose the game,” said Robinson. “Our chances tonight were easier than the ones Rangers took. We’re on a poor run of form and it’s not good enough.
“I’m going to have to change it in January. I definitely need two strikers and another defender.”