Rangers caretaker boss Graeme Murty admits Kenny Miller is a major doubt for the Old Firm derby at Celtic Park on December 30.

Miller tore his hamstring during Wednesday night's win at Hibernian and faces a race against time to be fit for Rangers' clash against Brendan Rodgers' rampant outfit.

It is another blow for Murty ahead of facing Dundee on Saturday after it was confirmed midfielder Graham Dorrans will be sidelined for the next three months as he recovers from ankle surgery.

Read more: Jason Holt: Josh Windass's goalscoring form is due to the belief Graeme Murty has given the entire Rangers squad​

Murty said: "We're hopeful it's not as big (a tear) as it looked, because it looked big.

"But he has quite a big range (of movement) and we're hopeful he's not going to be out for too long.

"However, the end of the year and the game at Celtic may come too soon for him. We'll just keep our fingers crossed and see how he progresses."

Dorrans has not featured since Pedro Caixinha's final game in charge against Kilmarnock almost two months ago.

And he is unlikely to be seen again before March.

Murty says that may force Gers to rethink their January transfer plans but he refused to discuss reports linking the Ibrox side with a move for Brighton midfielder Jamie Murphy.

Read more: Jason Holt: Josh Windass's goalscoring form is due to the belief Graeme Murty has given the entire Rangers squad

"We may (have to alter their transfer plans) as we were expecting Graham to be back in that area," said Murty. "Those conversations are ongoing but this may change the tone of them.

"We initially went down a conservative route on his ankle after medical advice.

"Unfortunately that did not bear fruit and he's now undergone a surgical procedure that will leave us without him for an extended period of time.

"We're hopeful it's not too long but we'll get a better steer on it when he comes back from London and we can get some more detail from the surgeon.

"It's a sore one for him as we were really hoping the first course of treatment would work and that hasn't turned out to be the case."