His performances this season had already demonstrated that fears that he might never be able to reach the standards he set before injury threatened his career were unfounded, but if the slightest doubt remained it was surely quashed by Craig Gordon's stunning double save at McDiarmid Park on Saturday.

Without it the 100 per cent winning run in 2015 which the champions extended to eight competitive matches would have ended at the most inconvenient of moments, immediately ahead of the meeting with Inter Milan which could elevate a season that already has potential for greatness into something of a different order.

Such was Brian Alexander's proximity to goal that an equaliser looked inevitable when the Saints substitute got everything behind his injury time header, but when Gordon's right handed block rebounded to Dave Mackay and he met the volley perfectly, the goal-keeper had no right to then shift to his left and turn it away.

"That's what happens when you're a top-class goalkeeper. He wins you points and that's what he's done today," Mackay was to observe ruefully.

Gordon admitted that his own reaction was out of character, but the way he punched the air, knowing his efforts had been comparable with any match-winning goal, demonstrated that even a man reckoned to have produced the greatest save in English Premiership history, knew he had excelled himself.

Thereafter, as the goal-keeper outlined how Celtic are increasingly gaining an understanding of their manager's outlook, it felt ever more significant that having apparently been brought in to help introduce some Continental thinking to the country's leading club, Ronnie Deila's first signing had been the Scotland goal-keeper.

Gordon has long been one of those keepers whose flexibility and reflexes make a mockery of the crusty old pros who seek to denigrate goal-keepers' contributions by suggesting they are not real footballers.

In reality most great teams establish their defences first and foremost and Gordon is now part of a rearguard that has a modern look about it in footballing terms, athletic and physically imposing.

As has been the case down the years when old-fashioned British sides have used their methods to upset Europe's finest, they will, of course, occasionally come a cropper when up against Scottish teams while, for all their efforts to adapt, Celtic's relative lack of exposure to the Continental scene may also make it difficult for them against the best in Europe.

However with Kris Commons, arguably their most gifted player, also recently having spoken about how he has sought to adjust to Deila's outlook, you sense that players - if not necessarily everyone in the Scottish football community - are readier to embrace the requirements of modern sport in terms of nutrition and preparation than was the case when Paul Le Guen was in town the best part of a decade ago.

Having also found, in his post-match celebration routine, a way of properly popularising himself with the majority of their supporters, there is a real sense that this Scandinavian is giving Celtic a chance of addressing the dilemma that faces them when domestic success is taken for granted, but the overall standard of competition is such that it is difficult to prepare for the European matches which give them a chance of generating wider respect.

Fighting on four fronts as they are, however, the composition and depth of their squad now looks such that they are giving themselves as much of an opportunity as they can to do so successfully within the limits of their competitive environment.

On which note Saturday's win was not the stroll to victory it could and perhaps should have been after, for the second time in four days the opposition resisted Celtic for little more than half a minute.

Three seconds earlier than the 38 it took to unpick Partick Thistle's defence the previous Wednesday, the champions were ahead and perhaps the biggest impediment to them capitalising on the way Leigh Griffiths slipped the ball under Alan Mannus after Nir Bitton picked out his run between the home side's central defenders with a pass from five yards inside his own half, was that the nature of the goal as well as its haste, had so easily put them in charge.

Caught cold as they clearly were, the Scottish Cup holders, who also had to make a significant early change when a calf injury saw midfielder Murray Davidson replaced by Chris Kane, responded commendably and while Celtic had chances to extend their advantage during the opening period, so did Saints as Lee Croft and Paul O'Halloran asked questions down either flank, while Mackay rightly observed that the enforced re-shuffle probably helped them respond following the setback of conceding so early.

When Celtic then scored early in the second half, Griffiths turning provider as his head pass diverted Stuart Armstrong's chip onto the chest of Stefan Johansen who never let the ball touch the ground in chesting it down, controlling it with his left foot, then volleying with his right, Saints again confronted the prospect of being overrun and again refused to buckle.

Gordon reckoned afterwards that Kane's closeness to him when deflecting Tam Scobbie's cross from the left goal-ward was why he could do no more than get a knee in the way, allowing O'Halloran to lash in the rebounding ball.

However any suggestion that the goal-keeper was at fault in offering St Johnstone late hope was rendered irrelevant by the quality of those decisive subsequent interventions.