James Lawton: Mourinho and Guardiola need to answer nagging doubts after chequered recent history
There's no doubting the achievements of Guardiola and Mourinho but both face questions from recent history
If boxing's Don King had ever thought of branching out into football he might now be on the eve of promoting Old Trafford as the Madison Square Garden of the world's most popular game. There has, after all, rarely been a heavyweight coaching title fight to match the one that goes down on the touchline at 30 minutes past noon tomorrow.
At least this is according to the super-fight hype that two masters at the peak of their powers are about to trade punches. But then at this early point in their latest campaigns do Jose Mourinho and Pep Guardiola really merit their old marquee billing?
About one thing we can be sure. Neither of them can easily afford the psychological damage that would come with finishing second in this particular collision.
While it may be true that in the restored capital of English football, Busby and Mercer/Allison and then Ferguson and Mancini had their Ali-Frazier moments, there is no doubt that for raw ambition, ego and the maintenance of Super-league mystique Mourinho against Guardiola is a fight that is surely going to be waged as much in the gut as the intellect.
Mourinho is insisting that he will do nothing to sharpen the edge of a rivalry primed by the knockout blow he delivered to Guardiola's Barcelona on the way to winning the 2010 Champions League with Inter Milan - and which at times blazed with open hostility when he moved to Real Madrid.
Indeed, he swears that he will revive the old Ferguson tradition of producing a bottle of vintage red wine for his opponent after the match. However, no-one should be lulled by the idea of clinking glasses and restored bonhomie.
This, we should make no mistake, is the coaching equivalent of hand-to-hand fighting, so much more than a mere contest of rival wills and technique and the highest reputation for that precious capacity to draw the best from some of the world's most expensive players. Some might even wonder if all the claret will come out of a bottle.
What is certain is that it is a battle for that prize which will always be the great reward for anyone who is obliged to publicly fight for his reputation. Along with a possible three Premier League points, this one also bestows the vital commodity of working creditability.
Astonishingly when you consider the scale of their coaching achievements, both men are in need of some of this despite their flawless starts at United and City as they sandwich Chelsea, and potentially their most dangerous rival Antonio Conte, at the top of the table.
It seems bizarre when you tot up Mourinho's eight titles, in three countries, and two Champions League wins, and Guardiola's six championships in Spain and Germany and two Champions Leagues, but the fact is they hardly need telling that they have much to prove at high noon.
Mourinho has to banish the idea that the disintegration of his Chelsea title-winners last season marked the ebbing of powers which once seemed to verge on the supernatural.
Guardiola too has to dismiss a question mark against a career that has left him generally recognised as the most innovative and inspiring football coach of them all.
At Bayern, he mopped up three Bundesliga titles but in the competition that mattered most, the Champions' League, there was a widespread belief that he had lost much of the brilliance that carried Barcelona to so many exquisite triumphs.
So are Mourinho and Guardiola fighting to stretch further their coaching reputations - or negotiating the first hints of burnout?
Guardiola did, after all retreat to New York for a sabbatical after walking out of the Nou Camp - a move that Ferguson warned him he might one day regret. "It is very rare to have such a group of players and when you leave behind the quality of such as Messi, Xavi and Iniesta you run the risk of wondering if you'll ever be so lucky again."
That old warning to Guardiola has now been accompanied by a somewhat withering verdict from United's former stalwart goalkeeper Peter Schmeichel, who argues: "He was okay at Bayern, I have to say he was okay, but for me he changed a really good, entertaining team to one more boring to watch. Whereas Bayern were before very direct, they won the treble, had quick players who were very exciting, he made them more square. He changed the players but of course you can't argue with the (Bundesliga) results."
Schmeichel also makes the Ferguson point that Guardiola had the greatest of luck when he inherited Barcelona's playing constellation.
"His results were fantastic there but you cannot forget the fact that he had the players who could put into practice his philosophy of possession and still more possession. Ferguson's priority was the same as most coaches, to score goals, but Pep made it possession in the belief that if you held the ball long enough you would inevitably score."
If Guardiola was not still so secure in his self-belief he might have already resolved not to delve too deeply into the in the current flow of professional opinion - and not least the regurgitated vitriol of his old player at Barca - and tomorrow's key opponent - Zlatan Ibrahimovic.
Included in that autobiographical diatribe was the assertion that Guardiola was a "spineless coward," in sharp contrast that was, to another former coach, fortuitously the one to whose care he has returned at Old Trafford.
Again, Guardiola displays the kind of forbearance that tends to settle in men only of the highest achievement. He says with barely a frown, "If I meet him I will greet him. I say again, I have to problem with him."
Nor, despite his barely concealed irritation with some of his antics at Real, Mourinho. "We are in the same business," he says, "and of course with great competition there is sometimes high emotion."
The odds-makers have Mourinho a clear favourite at 5/4, against Guardiola's 9/4, a leaning which might have a lot if not everything to do with the absence of Sergio Aguero through suspension.
For Guardiola, the best option might be to recall his head-to-head record against Mourinho, which shows seven wins, three defeats and six draws, and the grudging concession of his bitter assailant Ibrahimovic, who allows, "As a coach I have to say he is fantastic."
It is not the worst endorsement, given the source, and we can at least be sure of one thing. Madison Square Garden would certainly like the look of Guardiola at 9/4.