MARK WARBURTON has backed Niko Kranjcar to return to full fitness at Rangers as he waits to discover how long he will spend on the sidelines.

The midfielder suffered a knee injury last week and missed the Betfred Cup semi-final defeat to Celtic on Sunday.

Kranjcar has had a scan but it will be another few days before he can visit a specialist for a full diagnosis.

The 32-year-old could have played his last game this season but Warburton is confident he can make a comeback bid at Ibrox.

He said: “Niko is obviously frustrated, as much as I am, as much as everyone here is. Because we know how hard he’s worked.

“You know what it’s like yourself, if you go on a diet and target losing two stone in weight. You get there but you’re craving the biscuits and all that.

“Niko has been there but he’s done it. He’s done extras every single day, he’s in on his day off, been in here almost every single day.

“He’s gone back to Zagreb to see his daughter on a couple of occasions but, even then, he’s been working on the heart rate data we’ve given him.

“He’s been the ultimate professional and was reaping the rewards. So there is obvious frustration for everyone concerned.

“Of course he can come back. He’s 31, 32. If he was 37, 38, you might think differently.

“But he’s responded well to the quality of staff around him, the outstanding medical guys.

“We just had analysis for 45 minutes in there and he played a big part in that as well.

“With injured players, the danger is you can alienate them. We try not to do that here, we want them involved in everything we do. So there is no danger of that happening.”

The loss of Kranjcar is a major blow to Rangers as they bid to climb the Premiership standings after a poor start to the campaign.

The Croatian has scored three times in 15 appearances for Warburton’s side this term and has impressed in the last couple of weeks.

And the Ibrox boss is disappointed that he will be without one of his headline summer signings for the foreseeable future.

Warburton said: “I’m frustrated for him because a lot was made about his weight and his fitness.

“But Niko, we knew, had probably had three or four years of not being really pushed.

“The idea was to get him to nought to 30, then nought to 60, and then progress on.

“You saw the impact he had coming on as sub against Kilmarnock and Motherwell, then he started against Partick and in Inverness.

“He was having more and more influence so we’re so disappointed for him.

“He’s a top character and all the boys have so much respect for him.

“The physios said they’d never seen a reaction like it. All the boys came after training to say how he was – every single player.

“That shows you the esteem in which he’s held by the squad.

“He’s a very knowledgeable player, a very intellectual football player who knows the game inside out.

“His dad is obviously a pedigree coach and Niko knows a lot about the game. So the lads really respect him.”