James Lawton: The warrior who shaped Ferguson's empire

Roy Keane's departure from Old Trafford deprives the team of their heart and soul and ends the reign of the most influential player in the history of the Premiership

In the sudden wake of the Roy Keane era there is a single imperative, one that his patron Sir Alex Ferguson accepted as long as he could after the tumultuous good years turned into a time of pain and anger. From a critical distance we can only follow suit, and say as we do of the careers of most great figures: you take the best and live with the rest.

You live with the arrogance and the insults; the intolerance of all who do not fit into one man's fierce picture of what is right in a professional footballer and the organisation that surrounds him. You forgive the old bouts of drunkenness and the violence on the field that sometimes it was hard to separate from thuggery.

You do not compare this rough style - and Ferguson's need to bail him out of a police cell and defend him against charges that he had run out of control - with the grace and the statesmanship of a Sir Bobby Charlton, or the engaging manner of his immediate, warrior-like predecessor Bryan Robson.

No, if you do that you lose sight of the essential truth. It is that Keane was not only the heart and the soul of Ferguson's United. He was also the most dominant player in the history of the Premiership. This carried him as far as it could in a relationship always so potentially explosive. Yesterday time simply ran out on Keane and Fergie.

Plainly, the point of breakdown had been coming for several years. It had kept pace with the ebbing of the physical powers of a player who had been more than a leader.

He was no less than the guardian of the team's conscience. Ferguson didn't lightly give him the power of his master's voice, a privilege which turned horribly destructive recently when, like some disenchanted wolf, he snarled, so damagingly to the embattled leader of the pack. Ferguson gave Keane his huge leeway not out of affection but debt and the deepest of professional respect, because if Keane couldn't keep a dressing-room honest, nobody could.

Any review of Keane's performance, for both United and the Republic of Ireland, is inevitably clouded with ambivalence ... and paradox.

Nowhere was this better exemplified than in the ferocity of his rebellion in Saipan. Then, on the eve of the 2002 World Cup, he gave Ireland's coach Mick McCarthy no choice but to send him home.

Keane, far from the first time in his life, had given way to excess, this time in his judgement of the world around him. He wanted it to be not as it was but how he believed it should be, right down to the last detail.

For him it was impossible that Ireland's preparations should be less professional than those he had grown used to at Old Trafford, and if making the point involved a grievous blow to his nation's World Cup hopes, and the distribution of terrible insult to his coach and his team-mates, if it meant that his position as an icon of Irish sport would be perhaps permanently compromised, he made it clear that he could scarcely care less.

There was the ultimate contradiction because no one could have done more to carry the Irish team beyond their collective talent and into those World Cup finals at the expense of the Netherlands, a major football nation. On a leg that was becoming an ever-increasing challenge to medical science, Keane played the star-spangled Dutch to a standstill. He was, as always, the core of the Irish effort and the Dutch were just another team astounded by the depth of his will.

It is not easy to like a man who cares so little for the feelings of those around him. Once at an airport he was introduced to one of his greatest predecessors in the green shirt of Ireland; he grunted, and didn't look up. He lived in his own world, and nothing that had gone before or would follow could intrude upon that.

John Giles, as it happened, shrugged away the insult, saying, "There is a lot more about Roy Keane that I like than I dislike. Why? Because he was the most influential player of his age. He was the ultimate competitor and as United are finding now, he was utterly irreplaceable in what he represented." What was that, precisely? It was a competitive passion that rarely comes more than once a generation.

In polling of United fans, Roy Keane regularly runs second to the talismanic Frenchman Eric Cantona when the question of the best Old Trafford player of the Ferguson epoch is raised, just as he came off worst with David Beckham in lists of voting for the World and European Player of the Year awards.

But then ask Ferguson over a single malt who was the man who most shaped his empire, not for a day or a season, not in a burst of virtuosity, not in some Gallic flourish or mesmerising free-kick, but match by match, effort by effort, and the strong suspicion must be that he would nominate his turbulent Irishman.

Cantona unlocked the future and Beckham gave it skill and decoration. Keane was its warrior leader and, in a boisterous form of law and order, its policeman.

He didn't do it on his own, of course. Paul Scholes and Peter Schmeichel, Ryan Giggs and the Neville Boys, Denis Irwin ... the depth of United's drive was formidable, always, but when it mattered most, who was it who dug deepest, who threw his fist most defiantly to the heavens? Invariably it was Keane.

He did it in a way that makes a nonsense of all the tactical musings about diamonds and holding players, the man who sits and the man who goes. Keane was a holding player when he needed to be but did anyone ever go more wholeheartedly for the jugular? Did any of his generation ever read the game more acutely, or were any less likely to allow confusion if he had ever been put in the company of a Steve Gerrard or a Frank Lampard? No, Keane's way would have been the option, and for the best of reasons. It would be the classic way of the midfield general. There have been more graceful midfield operators. He didn't pass the ball like Glenn Hoddle, or create the brief wizardry of a Paul Gascoigne.

But what he did, and all the essentials were incorporated into his game, was with ultimate conviction and efficiency. The most unforgettable example of Keane's commitment surely came at the Stadio Delle Alpi in Turin in 1999, when United slipped two goals down in the opening exchanges of the second leg of the Champions' League semi-final against Juventus. United had been ambushed but Juve's timing was reckless. It gave Keane too long to rally his team and his blood. He scored the goal that carried United to the Nou Camp for the final and United's second trophy with a wonderfully arching header - and the fact that he had picked up the yellow card that would keep him out of the game proved utterly immaterial.

In similar circumstances in a World Cup semi-final, Gascoigne burst into tears. Keane merely clenched his teeth - and his fists.

Sooner or later the sinew of all men wilts, but in some cases not the spirit. We saw that well enough at Highbury last February, when United were required to make something of a last stand.

Keane faced down Patrick Vieira, for so long his one serious rival as the most influential player in the Premiership, both in the tunnel and on the field. Vieira had dared to throw around his weight in the presence of Keane, a dangerous thing to do at any time but suicidal at such a point of competitive tension. The Frenchman may have guessed that the fire had finally flickered down. He will probably always carry the burn marks that came from his miscalculation.

After Keane, what at Old Trafford? There is talk of Michael Ballack, hopes for Alan Smith and Darren Fletcher, and much scouring, no doubt, of the world market. But you cannot replace a Roy Keane. You can get various versions.

A Ballack would give you bold strikes from an advanced position in midfield. One day Smith's natural aggression might mature into significant value. Fletcher might overcome doubts about his pace and his force.

But a new Keane, a new roaring boyo from the streets of Cork City, a boozing, bar-clearing tearaway who knew quite how well he could play the game of football, and had the nerve to write to his first big-time manager, Brian Clough, to prove it? It is not likely.

Ferguson knows this better than any football man alive. Indeed, he took the best and he lived with the rest. It was, by some distance, his most decisive pact with glory.