I’m sitting in a pine-clad waiting area that feels like a changing room, in a tiny clinic in the centre of Munich, waiting to see the most enigmatic sports doctor in the world. He has reputedly cured every major injury-prone sporting name you can think of — Paula Radcliffe, José Maria Olazabal, Boris Becker, Michael Owen, Darren Gough. But he rarely gives interviews — or reveals his techniques.

He is Doctor Hans-Wilhelm Müller-Wohlfahrt — arguably the man who could shape the course of the forthcoming World Cup. Not just because he has been the German football team’s doctor for the past ten years and is using his unorthodox homoeopathic treatments to keep them at the peak of fitness. But also because dozens of the top players participating would never have reached the finals without Müller-Wohlfahrt’s remedies bringing them back from injury.

I am wondering how much credence to put on press reports saying that he achieves miracles by injecting his subjects with “cell parts from the foetuses of calves” and “juices from a turkey’s head”. And then out of the treatment room hobbles Linford Christie. “Ouch,” he says, as he tentatively pads towards me to collect his bag. And then the doctor enters, grinning, and slaps Linford’s hand (he does a lot of hand slapping). “I worked you well today, Linford, yes?” And he shows Linford out, both laughing like old buddies.

Müller-Wohlfahrt is a spookily well-preserved, lank-haired 63-year-old. He turns to me and enthusiastically clasps my hand in an airborne clinch that is obviously de rigueur for top sports people, but I respond clumsily. He shows me to a leather secretarial chair — previously occupied by the likes of Maurice Green, Asafa Powell and Diego Maradona. He’s clearly wary of me but has an immediate friendliness designed to put you at your ease.

His English isn’t great but he is keen to try and explain himself. He isn’t frightened of interviews, he says, it’s just that he sees no need for them. After all, his appointment books are always bulging with star quality, even though his “unorthodox” approaches have not been comprehensively researched. The cricketer Darren Gough was once quoted as saying: “Some people thought it might not be legal (he was referring to the injections) but look at all the people he treats. The guy knows exactly what he is doing.” Gough recommended him to struggling England captain Michael Vaughan, who has yet to make up his mind. So word passes from athlete to athlete, coach to coach — this man got me better, he’ll get you better. And it’s hard to find anyone who doesn’t agree that he does.

Professional colleagues, however, are more sceptical. Professor Arne Ljungqvist, a leading athletics doctor and a member of the International Olympic Committee, has warned that Müller-Wohlfahrt’s injections might end up breaking down patients’ immune systems. And even Healing Hans, as he is known, admits that there is little research base to his techniques. But he insists that he’s no quack: “I am an empirical doctor and, over 30 years, I have treated so many that nobody can tell me it doesn’t work. Nobody I have seen has had an adverse effect, or an allergic or other reaction.”

He did indeed qualify as a doctor of medicine in 1971, and completed his specialist training at the orthopaedic clinic of the Rudolf Virchow Hospital in Berlin. A keen athlete as a young boy, he became team doctor with the football club Hertha BSC in Berlin — and was then talent-spotted by Bayern Munich manager Uli Hoeness and Franz Beckenbauer and snapped up by Germany’s biggest football team in 1977, where he is still team doctor.

Since 1996 he has also been with the German national football team — though that doesn’t stop him from treating dozens of players from other countries, too. The doctor shows me a pile of reports he has just meticulously completed for world football body Fifa, documenting every treatment he has given to every player who will be playing at the World Cup (though he discreetly ensures I don’t see the names).

Worryingly for the rest of us, he assesses the Germans as among the fittest at the World Cup. Possibly even more worrying, the doctor confirmed he will be using his controversial injections on the team on a day-to-day basis to help them prevent and overcome injury.

So how exactly do his techniques work? He shows me a paper (detailed on theory, but with very little reference to existing research) that he has written about them for submission to the American Journal of Sports Medicine. “When I started as a doctor, I wanted to go deep into the metabolism, to accelerate healing,” he says. “A molecular biologist helped me understand what happens to muscle fibres when there’s a strain or a tear, and how infiltrations direct into the injury may help. At the time, colleagues thought I was crazy and at professional conferences audiences attacked me, but I went on and now other sports medicine doctors in Germany try to do the same, and there’s no discussion.”

By “infiltrations”, he means inserting fine, hollow needles into the site of an injury, or an injury-prone area, and then injecting through them preparations described as “homoeopathic” to activate the healing process faster than any conventional treatment, such as ice or rest.

Sometimes, as in the case of José Maria Olazabal — who famously went on to win the Masters in 1999 after treatment by the doctor (see panel above) — this can involve dozens of needles in the back, legs and feet over a half-hour session, repeated many times over several weeks. Or it may involve just one or two needles, inserted once. Müller-Wohlfahrt is a trained acupuncturist but denies that the technique works like acupuncture — needles are inserted on injury sites, not in “meridians”.

Müller-Wohlfahrt explains that for muscle injuries what he usually injects are highly dilute plant extracts — a product called Traumeel, apparently available in 60 countries. But he also injects an amino acid mix called Actovegin, derived from calves’ blood, to shorten healing time. For knee injuries, he uses Hyalart, a purified extract from the comb of a cockerel. In Germany, where alternative remedies and conventional medicine become confusingly mixed and are often practised by the same doctors, these products are manufactured, designed for injection and available to anyone at pharmacies.