The logic behind Neil Lennon bringing Fraser Forster back to Celtic on loan in August when he already had two Scotland goalkeepers in Scott Bain and Craig Gordon at his disposal was questioned by many.

Yet, the former England player, who had started just one first team game for Southampton in 17 months when he returned to Glasgow, has since justified what was a surprise move on numerous occasions, not least in the Europa League.

He was certainly the man who won the Betfred Cup for Lennon’s side, who were reduced to 10 men with the second-half ordering off of Jeremie Frimpong, against Rangers at Hampden this afternoon. He has turned out to be the signing of the season.

Christopher Jullien, the French centre half, scored the all-important, and hugely controversial, winning goal on the hour mark. But his side would have been soundly beaten had it not been for Forster. There was only one contender for the Man of the Match award when the final whistle blew.

Rangers were, by some distance, the better team over the course of the 90 minutes. They had 16 shots at goal and got seven on target. The Ibrox club could have had victory sewed up by half-time. But they were repeatedly thwarted by the brilliance of the man in the opposition goal.

Nobody suffered more than Alfredo Morelos. The Colombian, who failed to convert the penalty that Frimpong conceded when he was red carded, has now not scored in 11 appearances in the Glasgow derby match. You have to wonder if he ever will after this latest failure.

Lennon and his players had relaxed ahead of the final on Saturday night by taking in the world heavyweight title bout between Andy Ruiz Jnr and Anthony Joshua in Saudi Arabia in their hotel. It must have given them some inspiration. This victory was rope-a-dope and then some.

Rangers will, once the hurt of an inexplicable defeat subsides, perhaps take confidence from their impressive all-round display in what was an enormously entertaining encounter. But as they stood disconsolate on the sodden turf while their city rivals celebrated their 10th consecutive domestic success in front of their jubilant and relieved fans it was no consolation.

Steven Gerrard once again went narrow. Ryan Kent, Morelos and Joe Aribo pressed the holders high up the park and gave them no time to build play. The treble treble winners were forced to repeatedly shell the ball up the park to safety.

Lewis Morgan, up against the larger and more physical Connor Goldson, could do little with the inadequate service he received. The absence of Odsonne Edouard, who wasn’t considered fit enough to start, was keenly felt.

Scott Brown, Callum McGregor and Ryan Christie, normally so influential in the middle of the park, were hardly involved. Mohamed Elyounoussi, handed a start despite not playing in nearly a month due to a foot injury, was ineffective on the left. At no stage in the opening 45 minutes was Allan McGregor tested.

Forster, in stark contrast, pulled off several inspired blocks to keep his side level. He palmed away long-range Ryan Jack attempt that was destined for the top corner brilliantly and denied Morelos on no fewer than three separate occasions.

It was little surprise when Elyounoussi failed to reappear for the start of the second-half and was replaced by Mikey Johnston.

But the change made little difference. Celtic continued to live dangerously. Morelos saw a shot from an impossibly tight angle bobble agonisingly across the face of the goal and then had a header saved by Forster. The goalie also hooked the ball out for a corner as Aribo waited to pounce.

Rangers had a penalty claim ignored by referee Willie Collum in the 54th minute when Morelos went to ground in the Celtic box following a challenge by Brown. It would have been a soft award if it had been given. Contact, however, was definitely made.

There is always a danger in football when a team fails to capitalise on the chances they have created that they will pay a high price for their squandered opportunities. That certainly proved to be the case today. They fell behind against the run of play at a free-kick.

Goldson scythed down Edouard needlessly shortly after the forward had come on. Christie whipped it into the six yard box. Kristoffer Ajer, Edouard and Jullien were all, as television replays clearly showed, in offside positions when the playmaker made contact. But linesman David Roome failed to raise his flag. Jullien side-footed beyond McGregor.

It was an exquisite finish from the £7 million summer signing. But it shouldn’t have stood. Collum, however, had no choice but to award the goal. This showpiece match will lead to renewed calls for the introduction of VAR.

That was far from the end of the drama. Frimpong bundled over Morelos as he bore down on a loose ball three minutes later. Collum gave a spot kick and showed the offending player a red card. James Tavernier, who normally takes penalties, picked up the ball only to give it to Morelos. His team mate’s effort was poor and easily dealt with by Forster.

Celtic could, despite their numerical disadvantage, have built on their lead in the 69th minute when Edouard robbed Goldson of the ball and sent Johnston through. The winger should have buried it. But his final touch let him down and he sent it wide.

Gerrard put on Jermain Defoe for Kamara, Brandon Barker for Aribo and Nikola Katic for Filip Helander. His men continued to lay siege to their rivals’ goal.

But Lennon put on Nir Bitton for James Forrest, Ajer moved to right back and his charges dealt with everything that was thrown at them.