It is where neurology, biochemistry, psychology, dentistry and chiropractic are used to maintain fitness and to detect potential injuries.
Sportsmail's MICHAEL WALKER explores the background to the state-of-the art training facility which is the envy of world football . . .
Golden oldie: David Beckham
Old Trafford and the Champions League mean a lot to AC Milan - and not just because of that penalty shootout triumph over Juventus there in the 2003 final.
Three years earlier, Fernando Redondo's magnificent performance in Manchester for Real Madrid convinced AC Milan to buy him. They thought they were getting the best midfielder in the world, paying Real 15 million euros (about £13.5m) and Redondo three million euros for five years.
But Milan ended up with a crock and a medical determination to never again make a multi-million-pound mistake.
From there the club developed the famed Milan Lab, which is why tomorrow night, seven years on from that European triumph, no fewer than seven of Milan's 2003 starting XI and three used substitutes will again be in their squad. Five of them: Dida, Nesta, Gattuso, Ambrosini and Pirlo are likely to start.
At the San Siro they do not doubt that such longevity is due to the Milan Lab and its appliance of science in the field of sports medicine. Longevity is the goal.
The man behind this is a 63-year-old Belgian chiropractor called Jean-Pierre Meersseman, and the likes of Paolo Maldini and David Beckham have testified on behalf of Meersseman's methods.
'The fundamental concept,' Meersseman said more than a decade ago, 'is to determine whether the players are whole. And physical wholeness is the daughter of three mothers: equilibrium, endurance and co-ordination.'
That may sound a touch Californian but Meersseman's success is not in question. He was advising AC Milan in 1998 when he said that.
Survivor: Andrea Pirlo, who played in the 2003 final, is still in the Milan team
Meersseman had been doing so since 1986 but he was being given more control and in that first full season, Milan reported: 'Total practice days lost down 43 per cent, use of medicines down 70 per cent. Player injuries dropped by two-thirds.'
Forced to leave Belgium in the early 1970s as it was then illegal for doctors to offer chiropractic, Meersseman went to America. He was one of the doctors in the USA Olympic team in Los Angeles in 1984.
Next he went to France, then to Italy, where he set up a practice at Lake Como. In residence nearby was AC Milan owner Silvio Berlusconi. A connection was made that would see Berlusconi explode in rage at Redondo's breakdown, fire the existing medical staff and appoint Meersseman as medical director with a broad, powerful remit.
Milan mastermind: Meersseman (right)
'Since our model is deeply rooted in the philosophy, art and science of chiropractic, the medical staff were quite closed to the idea when I first arrived,' said Meersseman of the cull. 'So I had to fire the medical doctors who did not want to come on board.'
No longer was transfer money to be lost. Meersseman's prudent idea was to predict injuries, prevent them and thereby extend careers. Kinesiology is one of his key words: the study of human movement.
'Age doesn't exist,' he once told a Belgian interviewer. 'What counts is that you are physically and psychologically ready to play. It doesn't matter if you are 21 or 41.'
Meersseman would revolutionise Milan's system. In came neurology, biochemistry, psychology as well as chiropractic, kinesiology and plenty of staff. Dentistry is a significant factor.
A computer system developed in partnership with Microsoft pulls all the information together. While that is being done, players unwind in what the club describes as 'a glassed-in mind room'.
The club's willingness to talk about their Lab site at the Milanello training ground has led to others following, which is why Bruno Demichelis, Meersseman's partner, is now at Chelsea. And it all begins with a jump, or a dyna-jump.
'We did a pilot study on the analysis of a jump,' Meersseman has explained. 'You basically measure the angles of the knees with electromyography hooked up to the muscles. We measured flexibility, speed, etc, on a platform, and we had about 60,000 bits of data.
'If you put the data from the dynajump into the system of neural networking, the injury rate could be predicted with a 70 per cent accuracy, which is much better than flipping a coin.
Fat's the way: Young striker Pato undergoes a physical examination
'So, you could do an analysis of a simple jump, put it into the system and predict with a 70 per cent accuracy whether the player is going to get hurt or not. And that is interesting.
'If that is true, and all the mathematicians who work with us - and there are quite a few - confirmed these figures, it would be interesting to start accumulating data in all areas.
'We started to accumulate data from the structural area, i.e. how is the spine working, the teeth, feet, etc, and biophysical data plus the psychological data. We set up the Lab with apparatus that could feed the neural network and come up with results. Players are tested every fortnight and cause-and-effect data is collected every day.'
Beckham's body-fat percentage was sliced almost in half within days of his return to Milan. The 34-year-old midfielder's teeth were re-examined because teeth matter to Meersseman due to their skeletal relationship. He is said to have refused to sign off the purchase of Porto's Aly Cissokho due to a malocclusion.
Tennis player Kim Clijsters returned from Milan last year with a gumshield and saying: 'In the past I always had continuing hip problems. I got in contact with Jean-Pierre Meersseman from the Milan Lab, who tested me. First, I had to get used to it, but now I feel really good with it . I feel more stable and my bones react better in heavy matches. It's a small detail that can make a difference.'
Whether Meersseman can stimulate a second-leg Milan recovery at Old Trafford is another matter. It will depend on many small details, you imagine.
Alexandre Pato underwent a scan to help determine his readiness prior to flying out with the squad. That is one small detail, which includes another: that AC Milan still suffer injuries. Another is that Jean-Pierre Meersseman, medical guru, smokes.
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