Alan Stubbs believes Celtic are already assured of the cinch Premiership title and can now start thinking realistically about a domestic treble.

The Parkhead side moved six points clear of defending champions Rangers at the top of the table, with a vastly superior goal difference and just six games to play, after defeating their city rivals 2-1 at Ibrox on Sunday.

Having already secured the League Cup in December, former defender Stubbs sees no reason why his old club cannot claim a clean sweep of trophies, just as the squad he was part of in 2000/01 did under Martin O’Neill.

“I think the title race is over,” the 50-year-old said in an interview with the PA news agency.

“I think Sunday was a defining moment. Rangers have still got to go to Celtic Park, where I think the gap is only going to get bigger. Celtic can afford to lose two games and they will still win by goal difference.

“I think it is a foregone conclusion now. I would think the treble will be in their sights now. They’ve got one piece of silverware in the locker already, the league looks done and dusted, and they meet each other in the Scottish Cup semi-final, so I don’t think anyone would rule out the treble.”

Stubbs is stunned at how quickly Ange Postecoglou, in his first season in charge, has got his old club back to the top of Scottish football after a shambolic 2020/21 campaign in which the Hoops blew the chance of 10 league titles in a row by finishing 25 points adrift of Rangers.

“Could I envisage Celtic being in this position? Honestly, no,” said Stubbs, who was a Hoops player from 1996 to 2001. “I thought Celtic would certainly improve and I thought they would be closer to Rangers, but the transformation and the turnaround has been remarkable.

“Being honest, I don’t think any Celtic supporter would have thought they could turn everything round as quickly as they have.

“It was a huge rebuild. It wasn’t just on the pitch either, Ange inherited a situation off the pitch as well, because Peter Lawwell was moving on and a new chief executive came in who left pretty quickly. It was a changing of the guard and there were also recruitment issues.

“There was an awful lot going on off the pitch and on the pitch Celtic were in a mess from the previous season.

“Ange has come in and done nothing short of a fantastic job. His personality has certainly helped the situation. He comes across as a calm individual who knows exactly what he wants.

“Virtually every signing he’s made has been a success and it’s very rare that that happens.

“He has to take a lot of credit for that because, apart from the obvious ones who people knew, I think a lot of people were thinking, ‘Who? I’ve never heard of them’ with a lot of the signings, particularly the ones from Asia.

“But they’ve been brilliant and they’ve taken the Premiership by storm this season.”

Stubbs was impressed by the resilience Celtic showed at Ibrox on Sunday.

“Going into the game, there was a lot of focus on whether Celtic would be able to cope defensively with set-pieces and balls into the box, but they answered every question of them and more,” he said.

“It was a different Celtic on Sunday. It wasn’t the Celtic we’ve become accustomed to in terms of playing free-flowing football on the front foot. They did a bit of that, but the main aspect of it was that we saw a really disciplined defensive display that nobody thought they were capable of.”