James Lawton: As England's top order turns to dust, Morgan proves fit for the Ashes

England would have had a terrible time justifying their status as Ashes favourites if Eoin Morgan hadn't reminded not just his team but all of cricket that reputations sometimes can be built as quickly as they fall apart.

He scored a century of wonderful, rippling power and self-belief. He also said that some sportsmen will always refuse to be put into categories other than the ones they choose for themselves.

Morgan, the Irishman who has played his way into the heart of the most English of games, produced an innings here that might, if you didn't see the full picture, have suggested he had for a few hours roughly translated his spectacular one-day and Twenty-20 image into a workable version of the long game. The interpretation could only have been drawn from a set of statistics that included in his first Test half-century 10 sweetly struck fours, six of them coming in the space of 12 balls after Pakistan, led by their brilliant teenaged paceman Mohammad Aamer, harried the English batsmen to a parlous 118 for 4.

When Morgan walked to the wicket England had lost the heart of their batting, the South African mercenaries Kevin Pietersen and Jonathan Trott, in five balls and for an addition of just two runs, and with the 18-year-old Aamer moving the ball so well through the heavy atmosphere and his strike partner Mohammad Asif dismissing Pietersen so cheaply, the occasion called for rather more than a sharp eye and a big eye.

The Irishman not only met the occasion, he answered the most critical gaze that had ever alighted on him in a brief but meteoric career. He did it with cricket of a most superior kind. It had poise and depth and the kind of smooth resistance to pressure that England had so badly lacked as Aamer, with the wickets of captain Andrew Strauss, vice-captain Alastair Cook and potential anchorman Trott, threatened to do to them what he had so recently done to Ricky Ponting's Australians.

This was to say bowl them into a trance of indecision and broken nerve, a status they were holding off by a fingernail or two when Morgan arrived with so much easily controlled nerve it made a nonsense of his fleeting and less than overwhelming Test experience against lightweight Bangladesh earlier this year.

Naturally, Paul Collingwood eagerly formed a defiant alliance but this is the sort of thing the man from Durham does in his sleep and what was remarkable was how comfortably Morgan inspired and orchestrated the resistance.

In the end it helped that the Pakistan wicketkeeper Kamran Akmal, who had earlier missed the simplest of catches to dismiss Strauss, fumbled a mouth-watering chance to stump Collingwood. However, by this time Morgan and Collingwood had built a stand of 122, with the former scoring a first major success in his campaign to hold an Ashes place when the now firmly established Ian Bell returns from injury.

Morgan's first great crisis came when he was on 78. Sri Lankan umpire Ashoka de Silva gave him out lbw when Danish Kaneria got huge turn but a successful appeal to the Decision Review System saved the batsman – and his chances of making a stunning maiden century.

He celebrated his escape with a beautiful drive through the covers – a shot so easy on the eye, and so effortlessly produced, it made his earlier reverse sweep for a four seem like a mere, grand-standing trick from another game and another universe.

More than anything, Morgan was underlining the fact that on the approach to the Ashes series opportunity and disaster inevitably lurk with equal force. Certainly the horizons of both Trott and, most remarkably when you consider how high his stock stood not so long ago, Pietersen, can hardly feel secure in the great waft of the Irishman's huge move yesterday.

The question mark against him, inevitably, is that he is a virtuoso performer of a minor game, a man of splendid reactions and bold spirit but someone who has too brief a time to build a body of work to rival the senior players against whom he now competes for the great challenge of fighting Australia on their own soil.

For many, and their number surely took a significant leap here yesterday, the charge is less than destructive. If Morgan is a superb improviser, a man who can conjure his own shots for almost any circumstances, he is also a player who can play shots of impeccable and classic authority.

There were quite a number of these yesterday as Morgan so rhythmically built towards his first Test century. After the scare administered by Kaneria, there were certain hints of new pressure and some staccato bursts of aggression which draw the hero closer to his great prize. For Pakistan, who fought so hard to score a rare victory over Australia so recently, each stage of Morgan's progress was a fresh stab of disappointment.

And then, on the sunlit evening, he administered the clinching blow of a man who had seized his chance as perfectly as anyone who had ever played the game. He stepped forward and drove spinner Shoaib Malik high into the Radcliffe Road End. It brought the century and a statement of confidence in the future of English cricket and his place in it.

He may create more complete centuries in his time, compiled under greater pressure and against more mature and single-minded opponents, but it is unlikely that any of them will have the weight of such determination – and an understanding that these were perhaps the most defining moments of his career.

Certainly it is hard to believe that he will lose quickly the momentum that was created with the force of his confidence yesterday. He started the day a contender, a man who had to produce every scrap of his nerve and his talent to shape his future. He finished it a transformed cricketer, a man who knew exactly who he was – and where he was going.