Kevin Thomson insists Rangers can change the momentum of the Premiership title race with a win in Monday’s mouthwatering Old Firm clash.

But the former Ibrox midfielder admits defeat to Celtic would leave his old team facing an ‘astronomical’ challenge to rein in their city rivals.

Thomson has been impressed with the way new manager Michael Beale has kicked off life in charge of the Light Blues with a 100 per cent record following wins against Hibernian, Aberdeen, Ross County and Motherwell.

But, with Celtic themselves piecing together a 12-game winning streak in the league and seemingly hitting their stride at the perfect time, he knows the New Year derby is now ‘critical' in Rangers’ hopes of chipping away at the current gulf between the teams at the top of the league.

He said: “Nine points is a big gap, especially with how well Celtic are playing and how well Ange [Postecoglou] and his boys have done.

“They are a really good team and they’re battering teams. Every time you look at their stats, they’ve had 25 or 30 shots at goal, they’re winning by four or five.

“Yes, they have the odd wee hiccup, but they still seem to get over the line.

“So, it’s going to be a real challenge for Rangers to try to catch them.

“The mentality has to be that they believe they can get back in it [the title race].

“They’ve still got three Old Firm games to go and it’s amazing how football can change quite quickly. If they win in this derby game then things change, momentum changes.

“The scary thing, I think, for Rangers, and the harsh reality, is that Celtic are a really good team and they’ve been over the course. They’ve won 12 games on the bounce and they are battering teams, scoring a lot of goals and attacking with six, seven players. They’re relentless.

“So, that is going to be a challenge.

“There’s no doubt, at the moment, that Celtic are slightly in front.”

Speaking to Sky Sports, Thomson added: “Celtic will know if they come and win to go 12 points clear, [it] would be astronomical to try to close the gap.

“But there’s always that carrot that if Rangers can get a good, positive result then it can build momentum.

“If they are going to have any chance, I think this game is critical.”