Marcelo Bielsa, the Argentina national coach, took 1,800 football videos along with him to Japan. Then he decided he needed more, so he sent for another 200, just in case. After all, before giving Claudio Caniggia his first World Cup run-out in eight years he might want to have another peek at how he played during the final 10 minutes of Rangers' last home game against Aberdeen.

Or, in the event that Argentina should meet Cameroon in the final, he would be kicking himself had he discovered he had left at home the tape of the Indomitable Lions' 3-0 victory over Togo in the group phase of the latest African Cup of Nations. As for David Beckham, a player he hugely admires and against whom his team definitely will be playing, Bielsa will have brought along all his greatest hits - and probably his wife's too, for good measure.

No one could accuse the man who will be plotting England's downfall in Sapporo on Friday of not doing his homework. If any other coach, or - never mind coaches - any other person, has watched more football on television, more closely, over the last four years, he should be locked up. Bielsa himself has been locked up, since he got the Argentina job in 1998, in a ranch house in the Pampas, 200 miles north of Buenos Aires, watching football. Always at hand he has a collection of pens of different colours and stacks of sheets of paper, some blank, some lined, some marked with the imprint of a penalty area.

What he does, among other things, is break down each game he studies into five-minute segments, noting down with one colour pen which team controls which five minutes; in another colour the scoring opportunities; in another the percentage of possession; in another he sketches moves; in yet another he awards points out of 10. It is hard work. From 10 in the morning to 10 at night he toils: taping, editing, colouring, annotating, building up the most learned football library on the planet.

As the videos and the dossiers pile up, his solitary companion in the house, a taciturn elderly lady, sees to it that he is fed, watered and cleanly clothed. When he is not at the ranch, he is out, somewhere in the world, watching games - his own team's, or other people's. His wife, an architect, lives with their two daughters in Buenos Aires. There is no suggestion that either party is in any way unhappy with the arrangement. Weird stuff? Certainly.

There is a reason why in Argentina he is known as ' el loco Bielsa '. But there is method in his madness. His train-spotter's obsessiveness yields results. Argentina won the large South American World Cup qualifying group with almost insulting ease. They have lost only once (against Brazil, away) in the last 20 games. A lot of serious football people reckon they will be crowned world champions on 30 June. Along the way Bielsa has managed the singular achievement of winning over both the press and fans, who are so enraptured they barely uttered a whimper when he failed to pick two of their heroes - Juan Riquelme and Javier Saviola - for Japan. And, most important of all, he has overcome the biggest challenge facing managers at the top level nowadays: winning the unconditional respect of his multi-millionaire celebrity players.

Gabriel Batistuta describes Bielsa in his autobiography as the most important coach he has ever had. As well Batigol might, since it was Bielsa who discovered him in the late 1980s when he was tall, talented and far too fat; put him on a strict diet, fed him encouragement and turned him into the player who was to become the most prolific goal scorer of the Nineties in Italy's Serie A . Juan Sebastián Verón, speaking to reporters at the Argentine training camp in Rome three weeks ago, described Bielsa as 'Argentina's secret weapon' and explained: 'Over and above all else, I would like to say that we are very lucky to have with us a man as exceptional as Bielsa.'

What is so exceptional about him, aside from his manic attentiveness to detail? How does he inspire such devotion in his players? It is not charm, in the conventional sense of the word. He is not cool, calm and stylish like Sven-Göran Eriksson. Nor is he the type who aspires to become matey with his players. Terse, seemingly rather aloof in his bearing, he is a complex man who, like 90 per cent of middle-class Argentines, has spent many hours in psychoanalysis. Endlessly curious, instinctively inquisitive ('Bielsa knows everything about everything,' says Batistuta), he does not suffer fools gladly.

Argentine football writers all remember with a shudder the time when Bielsa, who never gives one-on-one, on-the-record interviews, uncharacteristically decided to sit down with one of their colleagues to dissect a series of intricate tactical plays. When Bielsa had finished he put the football writer to the test, asking him to summarise the lesson he had just learnt. When it became evident that the hapless hack had not been paying sufficient attention Bielsa became indignant and told him to stop wasting his time.

While sitting down and talking to Bielsa is never less than challenging, it would be a mistake to put him down as the mean, intellectual-bully type. It is more accurate to think of him as the mildly abstracted professor type for whom conversation is never idle. Tall, over 6ft, with wide-open staring eyes, and an exuberantly Beethovenish mane of hair, one could easily picture him as a physics boffin in a white laboratory coat. Or as a footballing Woody Allen, whose eccentrically likeable self-absorption, according to friends, he shares. One of his best friends is Jorge Val dano who, like Bielsa, comes from the town of Rosario but unlike Bielsa was a great player who won the World Cup with Argentina in 1986.

'Bielsa machineguns you with questions,' says Valdano, now sporting director at Real Madrid. 'You're at a restaurant and he asks the waiter, "Do you have pear tart?" "Yes." "And is it good?" "Very good." "Then could you give me a slice, but one big enough to accommodate a whole pear_" And so on. That's the kind of guy he is, but also he is the most fantastic friend to have.' He is also a man of principle. After winning the Argentine championship for the second time with the Rosario team Newell's Old boys in 1992, he gave his players permission to go to a wedding. But he asked them to get home by 1am because in a few days' time there was a cup game on. The players stayed at the party till five, Bielsa asked the club to fine the players, the club refused and, right there and then, Bielsa resigned. Bielsa prides himself on being a man of honour.

He will not be encouraging those such as Diego Simeone to try and rile the younger England players on Friday. He is uncomfortable with the win-at-all-costs cynicism of previous Argentina coaches like Carlos Bilardo. He despises, according to people who know him well, the type of football that places the emphasis on stopping the other team from playing. Which is why he admires, enormously, what he has privately described as the 'nobility' of the English game.

During a visit to England for Euro 96, when he travelled the length and breadth of the country on his own, he marvelled at people's passion for the game, at the depth and breadth of the football culture. And he is known to have a particularly high regard for David Beckham, whom he made his second choice (after Spain's Raúl) when he voted last time around for Fifa's world player of the year. The high regard he himself elicits as a man among his players, who are almost in awe of his intelligence and his high principles, is the platform on which they respect him as a coach.

Otherwise it might be hard to understand how it is that he persuades those such as Verón and Batistuta uncomplainingly to set about the extraordinarily rigorous, rigid and repetitive routines he imposes in training. He brings to the training field the meticulousness of the man who sits hour after hour scrutinising videos in the Pampas. And he translates what he has learnt during his hours of virtual-reality study into practical manoeuvres with ball and feet. If he wants to practise a particular move in a particular part of the pitch, say an area 20 yards by 20 between the centre circle and the touchline, he will cordon off with a rope that precise area, ask the relevant two or three players to step into the demarcated space and practise the move over and over until they can do it with their eyes shut.

And then there are the variations on a move. Players who have worked with him tell of practising the available options from a throw-in in a particular part of the pitch more than 30 times. What journalists have observed in the last few days in Japan is the spectacle of forwards like Batistuta, Crespo and Aimar being put diligently through their defensive paces, taught repetitively - as if the purpose were to memorise - how to hunt in packs, how precisely to choreograph their attacks on a defender depending on the part of the pitch where the defender is in possession of the ball. And here lies the key to the Bielsa style.

'Pressure,' he has said, 'is synonymous with football.' And also: 'Football is a collective game, it is - don't forget - a game of association.' By which he means that everybody attacks and everybody defends. The pressure on the ball all the time, wherever it might be, combined with the smooth, practised moves of a purring Mercedes Benz in midfield and attack, add up to the relentless, one-touch, high-tempo, total-football game that Bielsa has made his trademark and that Argentina's Latin American rivals have been helpless to resist.

How has he put together such a well-oiled machine? What is the key to his success? Oddly, given his almost manic disposition, where his genius lies is in his ability to communicate with his players. To reduce the clutter and complexity and odd-ballishness of his mind to short, sharp digestible messages that have the effect of bringing clarity and light to players' minds. One medium he uses is the videotape. Nelson Vivas, formerly of Arsenal and now with Inter, says that Bielsa's 'perfectionism', far from being irritating, has enhanced him as a player. 'The way he's got all the videotapes edited, to show you only what you need to know, instead of getting you bored with a whole match: it astonishes me.'

Two members of Bielsa's World Cup entourage are there solely to edit the vidotapes. Bielsa's other medium is the word. The son of a famous lawyer and the brother of a constitutional expert, Bielsa spends a lot of time thinking about the precise word or words he should use to instruct his players tactically and to uplift them emotionally. To this end it is a well known fact that he spends hours poring over dictionaries of synonyms. And it works. As Verón said recently, explaining what he meant by Bielsa being the secret weapon: 'He has the ability to make himself understood with a bare minimum of words and he has the gift of being able to motivate you into giving the very best of yourself.' Which, never mind the loco factor, is about as fine a definition as you will find of the perfect football coach.