IT ain’t over ‘til it’s over, so the song goes. But it’s over.

Celtic overcame some early stage fright to give their supporters the show they had rolled up to see, sweeping Hearts away to get the win they needed to remove the faintest scintilla of doubt over the destination of the Premiership title.

An early goal from Ellis Simms threatened to poop the party, but by the time Daizen Maeda, Jota, Matt O’Riley and Giorgos Giakoumakis had countered, the celebrations were in full swing all around Celtic Park.

Ange Postecoglou’s side will be worthy champions. This was their 30th consecutive league match without defeat, a level of consistency that was unthinkable when they lost three of their first six league matches way back at the start of this campaign.

It was fitting on the day that they started their long victory lap that Hearts were the opponents, as it neatly bookmarked the turnaround in Celtic’s season since those tumultuous days. It was Hearts who defeated Postecoglou’s side at Tynecastle on the opening night, after all. Who could have thought then that they would be heralding an impending title when they welcomed the same opponents to Celtic Park with matches still to spare?

This match was a microcosm of Celtic’s season in that regard, as the hosts overcame a somewhat sticky start to prevail, showing the mixture of fluid football and mental resiliency that has become their hallmark.

The only real selection dilemmas for Postecoglou were in the forward area, where he plumped for Kyogo yet again ahead of Giakoumakis, and gave Reo Hatate a rest in order to give David Turnbull his first start since his return from injury.

Hearts manager Robbie Neilson main priority was to keep players fit for the Scottish Cup Final, so while Stephen Kingsley came back into the side, John Souttar and Michael Smith were held back in reserve.

It was Hearts who started the brighter though, and Celtic seemed to still be napping as the ball was worked in from the left, the ball eventually finding its way to Simms off the foot of Liam Boyce. The striker appeared to be coming back from an offside position, but the foot of Carl Starfelt was playing him on and Simms wasted no time in smashing the ball into the net on the half-volley.

The malaise that was inflicting Celtic was epitomised in a tentative pass from Joe Hart into midfield, with Hearts forward Boyce inches away from cutting it out and surely doubling the visitors’ advantage.

Celtic needed a jolt, and they almost got it as Turnbull got a snap-shot away from the edge of the area that was matched by a sharp reaction save from Craig Gordon.

There were signs that the hosts were finally getting into gear, with Turnbull crossing for Kyogo who should have done better than glance meekly wide with a free header, and then Maeda flashing a ball across the six-yard box when found well by Greg Taylor.

The problem for Celtic was that any time they did get something on target, their former goalie was there to frustrate them, Gordon getting down well again to deny Kyogo as he got a sidefoot effort in from the edge of the area.

Celtic were cranking up the pressure though, and they soon had their leveller, as Jota burst through the Hearts defence before getting his head up and squaring for the arriving Maeda to finish first-time low past Gordon.

The goal wasn’t without its own controversy though, with the Hearts players protesting furiously that Callum McGregor had fouled Tony Sibbick – operating in an unfamiliar midfield role - in the act of winning the ball back for his side. Don Robertson was unmoved though, and Celtic smelled blood.

O’Riley galloped down the left and clipped a ball to the back post that had Gordon scrambling. Jota somehow got up above Alex Cochrane to nod down into the six-yard box, where Kyogo was sharpest to nod just over the line despite the best efforts of the Hearts keeper.

There was no such sluggish start to the second half from Celtic, who dominated the ball and patiently probed around the Hearts area. They came close to adding a killer third when O’Riley crashed a right-foot shot off the post from the edge of the area after his initial effort was blocked back to him.

On the hour, Postecoglou rang the changes, with Turnbull, Maeda and Kyogo taking a break and being replaced by Hatate, Liel Abada and Giakoumakis.

It didn’t take long for Abada to have an impact, getting Celtic out on the counter after a short flurry of Hearts pressure. The winger broke away down the right and switched the ball to Jota, who fed Taylor on the overlap down the left.

His deep cross found O’Riley lurking at the back post, who showed great composure to take a touch and place the ball across Gordon and into the far bottom corner.

It was party time, and everyone in green and white wanted in on the fun. As the clock ticked into extra-time, Giakoumakis got his name on the scoresheet, finishing clinically after being found by a clever cutback from fellow substitute James Forrest.

Postecoglou had urged his men to get over the line in style, and just like they have all season, they carried out their manager’s instructions to the letter.