David Weir believes it will be "really difficult" for his former club Rangers to close the gap on Celtic while Brendan Rodgers is boss at Parkhead.

The 47-year-old ex-Rangers defender was assistant to manager Mark Warburton two years ago when, as Championship winners, the Light Blues beat their old rivals in a penalty shoot-out in the William Hill Scottish Cup semi-final at Hampden Park.

The defeat signalled the end for then Hoops manager Ronny Deila. He was replaced by Northern Irishman Rodgers, who has not lost in nine Old Firm fixtures since, winning seven of them.

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Weir and Warburton left Ibrox in February 2017 after falling well behind Celtic in the title race, and Rodgers' side are now chasing an historic second successive treble.

Speaking at a William Hill media event at Hampden Park ahead of Sunday's Scottish Cup semi-final between the Old Firm rivals, Weir said: "I think it will be really difficult (for Rangers to close the gap to Celtic). He (Rodgers) is a top manager. He has a method in regards what he does.

"He has the respect of the players, the club, everybody and he is setting the bar high.

"Celtic's managerial appointment was really good. There was obviously a lot of thought and planning went into it.

"They picked the right man at the right time and he has shown their faith was right."

Weir believes Rangers carry a "similar" underdog tag into Sunday's meeting to they one they overcame two years ago.

He said: "It has been a long time not to have won an Old Firm game. Celtic have obviously improved from that day, no doubt about that.

"Celtic had probably the better chances in the game but we took our chances and we got a bit of luck.

"So it is a massive challenge but also a good opportunity for Rangers to put a marker down.

"I think Rangers have a chance, definitely. The past couple of Old Firm games have been tight.

"Celtic have managed to come out on the right end of it. Rangers have had opportunities in the game but unfortunately they haven't managed to do it."

Speculation surrounds the future of the current Ibrox incumbent Graeme Murty, but Weir reckons a semi-final win would go a long way to helping him secure the manager's job on a longer-term basis.

"Graeme has done really well," Weir said of the 43-year-old, who was handed the reins in October on a caretaker basis following the sacking of Pedro Caixinha and in December appointed until the end of the campaign in December.

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"We brought him in as an under-20s coach from under-18 football at Norwich so the jump has been really quick and far in a short period of time.

"He has coped with that really well. He has been put in a difficult situation and he has handled it well.

"Rangers are competitive, they are fighting for second place (in the Ladbrokes Premiership) so that will be a success this season and they are in the semi-final of the cup.

"Is he right man for the job? Time will tell but winning the semi-final and finishing second in the league will certainly help that.

"I am sure he won't be thinking about his long-term future but for Rangers it is important to win the semi-final.

"It has been a long time since Rangers have beat Celtic. So that must be a great motivation, whether it is for Graeme's future or anyone's future."