Ally McCoist insists it would be “unthinkable” for Rangers to lose next week’s Old Firm crunch.
The Ibrox hero reckons the gap at the top would be too big for Gio van Bronckhorst’s side to overcome should they slump to a damaging derby defeat.
But McCoist is confident his old club will rise to the occasion and ensure the defence of their title will go to the wire.
And he reckons Aaron Ramsey is a key man to help them do just that - if the Wales midfielder can prove to van Bronckhorst he is fully fit and ready to be thrown into the cauldron.
Celtic lead Rangers by three points going into the encounter although a vastly superior goal difference means the gap is slightly wider.
And McCoist said: “From Rangers’ point of view, defeat is unthinkable. I think that would make the gap far too big.
“I don’t see that though. Both teams have got a bit of form. Rangers in Europe have been excellent, domestically form has been a bit up and down.
“They had a massive win at Dundee when they didn’t play particularly well. They are hanging on to Celtic’s coat tails.
“I think with this game coming up we will see a different Rangers, I really do. It is a game that they certainly cannot afford to lose.
“I think they will go out and go about their business in a manner that they have to win the game.”
Ramsey has started only three times for Rangers - against Annan and Dundee twice - but completed a full 90 minutes for Wales as they booked a World Cup play-off final spot with a 2-1 win over Austria on Thursday.
The 31-year-old arrived on loan from Juventus on deadline day in January but his game time has been limited due to fitness issues.
McCoist hopes he’s ready to play his part in the run-in starting in the biggest fixture of all this weekend.
He told Sky Sports: “He's class isn't he? He's a wonderful football player.
“It's been highly documented that he's struggled a little bit with injuries to keep him 100 per cent fit which is a great shame because we all want to see good players on the pitch and he's certainly that.
"He'll have a real bonus after scoring his first goal up in Dundee and I think he played the entire game for Wales.
“That's a real positive in terms of his fitness and I'm very hopeful that he can get his feet up, have a rest and get himself ready for this Old Firm game because I want to see Aaron Ramsey playing in that."
The derby spoils are even after two outings so far this season and, while McCoist is confident Rangers will do the business in front of their own supporters, he has been impressed with the job Ange Postecoglou has worked on the other side of the city.
Celtic are 31 games unbeaten domestically.
And McCoist said: “This is one of the biggest Old Firm games. We keep saying it, I feel as though I have said this 4,011 times.
“It is certainly the biggest Old Firm game for a while. I don’t think Rangers can clearly afford to get beat.
“Ange Postecoglou has done a great job at Celtic. They have got themselves in a very, very good position.
“I think there are three games coming up over the next month or so if you include the Scottish Cup semi-final.
“There certainly won’t be a dull moment north of the border, particularly in the Glasgow area.”
