Rangers icon Brian Laudrup is convinced his former team have the ability to "turn the tide" and land a signature win over Celtic.
The Danish wing king pulled no punches in the wake of the Premiership champions' 3-0 defeat to the league leaders in February.
But he is backing them to get a valuable result this time around.
Rangers gave up top spot in Celtic Park and currently trail Ange Postecoglou's side by three points heading into the blockbuster encounter at Ibrox.
And Laudrup's belief centres around three players who didn't start on a sobering night for Gio van Bronckhorst 's side.
Speaking in his Daily Mail column, he said: "You can take your pick of adjectives to describe the performance Rangers produced in the last Old Firm game.
"Awful, shocking and unrecognisable would be just a few. Maybe you could even say that first-half capitulation was rather spineless. But I fully expect a completely different showing in Sunday's epic encounter at Ibrox. In part, because I hope Rangers will have a very different spine to their team.
"Alfredo Morelos, Ryan Jack and Leon Balogun. None of those players started the 3-0 loss at Celtic Park on February 2. With varying degrees of importance, having them back could make a world of difference to how Rangers deal with this derby. And to their prospects of retaining the Premiership title.
"The pressure is well and truly on now. Giovanni van Bronckhorst's side have to win. If they lose, and go six points behind with six games to play, it's pretty much game over in my view.
"But Rangers have what it takes to turn the tide. I firmly believe that. And they will ask Celtic a whole other set of questions if they can call upon that aforementioned trio of players at the end of this international break.
"Morelos is the biggest concern after news he was sent home from Colombia duty because of a thigh muscle problem. Hopefully, from a Rangers perspective, there is time for recovery ahead of the weekend.
"Because it's critical to have him leading the line.
"We know he's not been as prolific in these derbies as he has in the Europa League, but his presence on the pitch will worry Celtic. They know how annoying he can be. The menace he can present. As an opposition defender, you need to constantly have an eye on him. You're aware he can drag the his whole team up the pitch through his smart movement and strength."
Laudrup believes both teams results in Europe can also prove pivotal when they lock horns during Sunday's High Noon showdown.
Celtic were well trounced 5-1 on aggregate by Bodo/Glimt in the Conference League while Rangers are flying high in the last eight of the Europa League.
He added: "Rangers can draw belief both from their own high-level performances in Europe and how Celtic stuttered on that stage.
"Look at what Bodo/Glimt achieved against Ange Postecoglou's side by really being on the front foot against them, with a clear understanding of their gameplan.
"Now, the Norwegians are a good team you don't thrash Roma without being that but they made it extremely difficult for Celtic by applying a lot of pressure.
"I'd be surprised if Van Bronckhorst didn't take things from those matches, as well as learning the lessons of Parkhead.
"That night, Rangers found incredibly difficult to cope with the overloads and combinations Celtic were able to create in wide areas. It seemed to almost come as a surprise, which was strange because everyone had seen how Postecoglou (pictured) wants his team to play. Changing style doesn't seem to be in the Australian's nature and why should it be when he has turned the tables on Rangers to gain the upper hand in recent weeks?
"The Parkhead outfit will rightly travel with confidence after going 31 domestic matches without defeat. Plus they have the psychological lift of their last Old Firm experience.
"Even if Celtic lose on Sunday, they will still have a goal difference advantage.
"But it would shift a lot of the mental burden towards this recently-assembled Parkhead squad.
"If your fiercest rivals are coming on strong with just six games to play, that could make some Celtic legs a little shaky. It would be a big test for the newer players in terms of how they react. All this is just conjecture for now, of course. To make it into a real test of nerve on the finishing straight, the Ibrox club have to win on Sunday. And that will be a lot more likely if they have Morelos and Co to call upon.
"It's critical that Rangers have a fit Morelos to lead the line."
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