Coach with no time for fancy-dan footballers is one win away from Champions League glory

Louis van Gaal's first act as Bayern Munich manager was to shut himself in a monastery for a month. Inspired by its ascetic ethos, the Dutchman totally immersed himself in the intensive German lessons offered by enterprising monks and emerged with more than merely a decent grasp of modal verbs.

Most managers would refuse even to contemplate spending a large chunk of the summer break cloistered away from secular society in an abstemious parallel universe, but Van Gaal's retreat into a religious order this time last year proved emblematic of the 58-year-old's modus operandi.

Startlingly left-field, yet intensely conservative, eminently logical, but invariably imaginative, Van Gaal is a supreme strategist whose blend of industry and innovation has helped him to choreograph four teams in three countries to 18 major trophies, the latest with Bayern's 4-0 demolition of Werder Bremen in the German Cup final yesterday.

Aware that Bavarians expect Bayern's manager to speak their language, he typically mastered essential German in the fastest possible time. Next up was the initially vexing, ultimately successful mission to become the first Dutch coach to win the Bundesliga and, now, Van Gaal is attempting to squeeze even greater job satisfaction from his inaugural season at the club dubbed "FC Hollywood".

On Saturday, in Madrid, club football's most glittering prize is up for grabs when a martinet capable of accruing enemies even faster than silverware aims to mastermind a Champions League triumph at Internazionale's expense.

Already, a German media bearing scars inflicted by the former Ajax, Barcelona, Holland and AZ Alkmaar coach's infamous sarcasm has dubbed a clash that pits him against his one-time assistant at Barcelona, José Mourinho, as "God v The Son of God".

Despite both boasting out-size egos, the pair remain good friends, regularly exchanging warm texts as they bask in the European limelight.

"This is going to be one Champions League final where the coaches, rather than the players, dominate attention," Glenn Roeder says. In 2007, the then Newcastle manager was "Van Gaaled" when AZ knocked his side out of the Uefa Cup after an extraordinary second leg in Holland. It began with the sound of a high-volume recording of Winston Churchill's "We shall never surrender" speech crackling over the stadium Tannoy as kick-off beckoned, as the home manager, trailing 4-2, sought a psychological advantage. "You can never overestimate Van Gaal," Roeder adds. "He's one of the world's great coaches; José Mourinho won't be complacent."

Mourinho says that while the late Sir Bobby Robson taught him the value of shrewd man-management, Van Gaal highlighted the importance of preparation and strong defence.

If both finalists are very much systems men, sharing an almost evangelical belief that, by dint of tactical ingenuity, the manager is king, they remain far from footballing soulmates.

Van Gaal remains considerably more attack-minded than his Portuguese rival, permitting significantly greater scope for improvisation within the parameters of any tactical framework, but Mourinho's man-management is considerably more evolved. Many would say it possesses the emotional intelligence lacking in his unashamedly old-school mentor, who was required to rebuild a reputation shattered by a disastrous stint in charge of the Dutch national side, culminating in the so-called Clockwork Oranje's failure to qualify for the 2002 World Cup.

You would certainly be unlikely to catch Inter's coach emulating Van Gaal and screaming insults in the face of Franck Ribéry after the over-heated winger dared to sit down and take his boots off during a scorching training session last summer. Or to see Mourinho spot Luca Toni slumping in the canteen over lunch and immediately stride over, angrily pull one of his ears and order him to sit up straight.

Although Toni is now on loan at Roma and Van Gaal's relationship with Ribéry remains uneasy, the realisation among Bayern's players – particularly younger homegrown ones – that he is capable of improving them beyond recognition permits him to take some breathtakingly Clough-like liberties.

It is no coincidence that the 20-year-old forward Thomas Müller and the 21-year-old defender Holger Badstuber have emerged from the youth ranks to keep Ribéry and company unexpectedly on their toes during a season when Bastian Schweinsteiger has also surpassed himself in midfield.

Roeder adds: "Van Gaal generally has more success with younger players who fully appreciate what he's doing for them than with more cynical older stars; maybe that's why his time in charge of Holland didn't work out. But he's a brilliant, brilliant coach and even difficult players respect that."

At Bayern, it also helps that he is not Jürgen Klinsmann. Supporters had come to loathe their former manager's Americanised obsession with image and swiftly realised Klinsmann's slickly spun, relentlessly positive soundbites, plastic smiles and careful placement of Buddhist statues in training-ground lounges masked clay feet. Tactless and taciturn, Van Gaal was eagerly embraced as an "authentic" antidote.

In return, Bayern's so-called Tulip General is seeking to relight the flame of perfection he first sparked when his Ajax team – which featured, among many other extravagant talents, Jari Litmanen, Frank Rijkaard, Patrick Kluivert, Marc Overmars and Edgar Davids – effectively redefined Total Football.

"We play very attractively at Bayern," says Van Gaal, a stickler for formal manners, who faced the sack last autumn after indifferent results. "We are always looking to attack and put opponents under incredible pressure."

It has been much the same since Aloysius Paulus Maria van Gaal exchanged life as a slow and stocky, but eye-catchingly sweet-passing, Sparta Rotterdam midfielder for a coach's tracksuit at Ajax.

"I have my own ways, I'm not going to change and I have no desire to," says the unusually unmaterialistic multi‑millionaire, who, to his wife's dismay, disdains fancy restaurants, designer watches and male fashion. "My way is a footballing philosophy more than a system. A system depends on the players – I've played 4-3-3 with Ajax, 2-3-2-3 with Barcelona and 4-4-2 with AZ – but a philosophy is for life.

"The coach is the team's focal point, so preparing the tactical formation is essential. Every player must know where he has to be and support his team-mates. There has to be absolute discipline and mutual understanding. Discipline is the basis of creativity and flexibility."

Although he claims immunity to the vagaries of popular opinion, Van Gaal does sometimes bend his rules, slightly. At Barcelona, where his falling out with Rivaldo over the Brazilian's penchant for unscripted dribbling still raises eyebrows, he compromised over the training regime. "Spanish players refused to do the running he demanded," Roeder says. "So he introduced the ball to every session. The players thought they'd won, but ended up running just as much."

Despite his formidably cold, cutting and sometimes contemptuous public persona, Van Gaal has aspiring coaches jostling for placements under his wing and Adam Sadler, the former Norwich City assistant manager and now No2 at Gateshead, visited AZ as part of his Pro Licence.

"I had sky-high expectations," he says. "But Louis van Gaal exceeded them. He was welcoming and open. He's a man of integrity and strong moral values who demands maximum concentration. He doesn't let players relax."

In past years, the Dutchman has claimed to be coveted by Manchester United and England, but Roeder questions his suitability. "Van Gaal spends hours on passing drills and technique," he says. "They're things a lot of English players don't enjoy – which is why we're not as good, technically, as we could be."

During the dark days of last autumn, when Bayern drifted towards Bundesliga obscurity, there was a feeling Van Gaal might not be right for Munich either. Elimination from the Champions League group stages looked likely, dressing-room dissent festered, everyone was mystified when he deployed a 3-3-3-1 formation against Hamburg and dismissal loomed.

A watershed arrived when the still-struggling coach addressed Bayern's important AGM in November. Privately thrilled by his uncompromising refusal to bow to chairman Karl-Heinz Rummenigge's demands for weekly debriefs and a consistent two-man strike force, the audience greeted Van Gaal's startlingly honest speech with wholesale applause. Dressing-room rebels took note, the manager mellowed a little and a corner was turned.

Although fortune continued to smile on Bayern's less-than-serene Champions League progress, their one- and two-touch game was turning into an art form, a reborn Mark van Bommel invariably controlled midfield and a miraculously fit Arjen Robben revelled in the form of his life.

Much to the relief of his second wife Truus, Van Gaal – whose first spouse, Fernanda, the mother of his two daughters, died of cancer in 1994 – had once again prevailed against adversity. "Louis is actually extremely warm-hearted, but he doesn't get the idea of being nice to people he doesn't think are nice," she says. "He's also very honest and naive. Almost no one is as honest as him. It makes life difficult, but Louis has this complete belief in himself and his methods."