Scott Arfield has a "significant" ankle injury that is expected to sideline him for the rest of Rangers' vital January run, says boss Steven Gerrard.

The midfielder sat out last weekend's Scottish Premiership win over Celtic after damaging ligaments against Hibernian on Boxing Day.

He is set to miss away games at Aberdeen, Motherwell and Hibs and a home meeting with Ross County.

"It's an injury you can't really push," said Gerrard.

"Scott's about to come out of a boot that he's been in since the injury. He's progressing well but in the short term Scott will be missing.

"He's got quite a significant injury. We are probably looking at four to five weeks."

Striker Kemar Roofe will also miss Sunday's game at Aberdeen after a quad injury forced him off at half-time in the Old Firm victory which sent Rangers 19 points clear at the top.

But midfielder Ryan Jack is nearing a comeback after more than a month out with a persistent knee problem.

"Kemar won't be with us at the weekend," Gerrard added. "It's difficult to put a date on that one just yet but I predict he could miss a couple of games.

"There's better news on Ryan Jack, who has had two or three sessions and is progressing extremely well. If that keeps moving in that direction he should be back with the team in the middle of next week."

Meanwhile, Gerrard confirmed he is set to trigger Rangers' option to extend Leon Balogun's one-year deal after the Nigeria defender's impressive form since joining from Wigan Athletic last summer.

Derby hero Allan McGregor is also entering the final six months of his deal but Gerrard is happy to let the goalkeeper - who turns 38 at the end of the month - decide his own future.

"There's no talks with any of the players at the moment but that doesn't mean that we're not keen to keep them," Gerrard said.

"Allan's in fantastic form and we're really pleased with him. I think Allan's situation is a bit different than most because of his age.

"It will be a case of what Allan wants to do, so at the right time I'll sit down with Allan and have an open discussion on that one.

"Leon is someone we want to keep hold of. He knows that, he is performing ever so well. He signed a contract with an option of an extension and we want him to be here beyond this season."