SWIMMING PROFILE OF MICHAEL PHELPS: Keith Dugganon the man still hoping to out-medal Mark Spitz

IF MICHAEL PHELPS at last eclipses Mark Spitz, the 1970s sun god of swimming whose haul of seven golds has yet to be equalled, he could not choose a more magnificent arena in which to do it. The Baltimore phenomenon has spent almost half his waking life in swimming pools but even he confessed himself blown away by the Beijing arena, a dreamlike, fluorescent-blue cube that, like the main Olympic stadium, is nothing short of a marvel.

During the training practice on Thursday, the appearance of Phelps signalled a minor outbreak of pandemonium at poolside as swimmers from other nations abandoned laps to have their photographs taken with the feted American.

Phelps has changed greatly from those Athens nights when, as a gauche and lanky teenager, he stormed his way to four gold and two bronze medals but was still branded as something of a damp squib after his widely heralded bid to match Spitz never really caught fire.

At 23, Phelps has added 15 pounds of lean muscle and the boy prodigy has become a man. He has swapped the conventional high-school-photo look for a scruffier, retro image complete with a surfer's tash that may well be a homage to Spitz himself.

As Phelps mixed with the swimmers whose feats will be utterly overshadowed by the huge bubble of speculation and hype his brilliance has generated, he looked happy and relaxed. When Phelps grins - which happens frequently - his long faces seems to fold like an accordion; his eyes crease up and his cheeks squash up and he presents this huge, toothy, open smile.

With the long, strange frame and the sticky-out ears and that huge, warm grin, Phelps is a cartoonist's dream, and he must be the most easily recognisable athlete staying in the competitors' village.

The popular portrait of Phelps is of an easy-going and likeable fellow, a typical goofball who just happens to have the ideal physique for competitive swimming. And Phelps's public demeanour, sauntering through his Olympic public duties as though he has not a care in the world, lends substance to the pretence he is a slacker-champion.

On Wednesday, when he drew a huge attendance to his press conference, Phelps was predictably "so-what?" about the fact the Spitz-Phelps hype machine is at full throttle again.

"You guys are the ones who are talking about it - I'm not saying anything," he said in cheerful rebuke.

Phelps has become accomplished in saying nothing but if there was any significance to be gleaned from his public utterances this week, it may have been in a casual remark he made about why he continues to stay in the athletes' village.

Phelps is up there with Kobe Bryant and Roger Federer as one of the Olympians capable of causing other athletes to become star struck, but he still opted for the chumminess of the village rather than sequester himself in some plush penthouse with a sweeping view of the Beijing skyline.

"I never experience the college dorm before so I guess this is pretty much like that," he confided and talked about the fun of lounging around with his swimming team-mates and just "goofing off".

Somewhere at the heart of that observation there is the faintest glimmer of how strange and solitary the everyday life of Michael Phelps must be. He has measured his world, his existence, in terms of 50-metre laps reeled off in the broad repertoire of strokes in which he excels.

Like Mozart, Phelps was identified as a prodigy, but unlike the composer, the modern-day swimmer has seen little of the wild life.

"You knew it as soon as you saw the body," said Bob Bowman, his coach for the past 10 years. "At 11, he had everything he has now, only smaller."

Phelps's physiology has become a subject of intense study for sports scientists. Like every other sport, swimming has been rigorously broken down. It is not simply the swimwear - Spitz swam to immortality in Munich wearing a pair of conventional Speedos and goggles, while Phelps wears a highly technical body suit that can take up to 20 minutes to get into.

Swimming, like so much of athletics, is about the relentless quest for faster times, for pushing the limit of human capability. In Phelps, they have a man who has pushed out onto the plains of an unimaginable frontier.

Bowman, an intense and scrupulous figure who swapped a life in music to coach swimming, has been open about the fact he essentially put Phelps through torturous rigours to shape the swimmer he would become.

When Phelps was in early adolescence, Bowman had him swimming 50 miles a week to work his heart and lungs in a way that would not be possible in his later teenage years. Those mind-numbing laps, on lonely mornings in his training pool in Baltimore and, later, at the Wolverines club in Ann Arbour, Michigan, were crucial in shaping the specimen Phelps has become. Genetics did the rest.

Phelps has a 6ft 7in "wingspan" and the flexibility of a limbo dancer. He is a tall man at 6ft 4ins but he is almost all back: he has the compact legs of a football player or a surfer and then has two huge feet.

He can look ungainly walking around - he once owned up to being "the klutziest person on earth" and had running eliminated from his training schedule by Bowman because he kept falling over. In fact, he could have jeopardised his place in these Olympics when he had a bad fall after tripping while climbing out of his car on an icy morning in Michigan.

If Phelps's handlers could wrap him in cotton wool, they would. For in the swimming culture, he is a phenomenon. One of the enduring legends is that he produces much less blood lactate than his rivals - about 5.6 millimoles per litre of blood - as a consequence of his superb aerobic conditioning. That statistic was recorded after he broke the 100 metres butterfly record in 2003.

Since then, little technical data on Phelps's physiological make-up has been released into the public sphere, but there has been a general acknowledgement that even though he swims like the proverbial fish, he is human - albeit like no human previously seen in water sport.

Even to our untrained eye, it is clear Phelps moves with untold grace and comfort through the water, as though the water were his natural habitat. But even to the experts who study and analyse his every stroke, there is an element of mystery about how he can do what he does.

"People aren't made to move like that," remarked Russell Mark, the biomechanics manager of the USA swimming team, in a recent interview.

Although the Olympic swim races are over in a matter of seconds and the swimmers usually emerge from the water looking invigorated and smiling, the reality is more brutal.

Swimmers spend the dawn hours and tedious late afternoons in the silence of the water so that they can build up water fitness inconceivable to most people. It would seem Phelps is capable of enduring fatigue in a different realm from what will be experienced by other athletes.

One study suggested that if Phelps's Beijing schedule is similar to what he did in Athens - and he is entering eight medal events here - his combined swims will be the equivalent of running eight to 10 full marathons over the duration of the Olympics.

In other words, Phelps will go through a physical regimen at these Games that would kill many athletes. And he will do so watched by billions of people.

Four years ago in Athens, Phelps managed just a bronze medal in the event that was billed the Race of the Century, the 200 metres freestyle.

That race was a valedictory for the great Australian Ian Thorpe, who took gold. Pieter van den Hoogenband, the seemingly ageless "Flying Dutchman", took silver.

Phelps took the disappointment with good grace, but amid shameful scenes afterwards, he had to defend the fact that he had "merely" taken bronze, the press hordes behaving as though they had been duped by the seductive story of the bid for seven gold.

He has learned from the fickleness of that night. And with Thorpe in retirement and van den Hoogenband concentrating on the 100 metres freestyle, the 200 metres event should his and his alone. In fact, the only competitor people seem to feel Phelps is racing against is that ghost figure of Mark Spitz, swimming in a parallel lane but separated by the mere matter of 36 years.

It is one of the many paradoxes of the Olympics is that swimming, virtually an underground sport in normal years, enjoys a huge following for these few weeks. Most swimming stars have the competitive lifespan of butterflies and their Olympic moment is everything.

Phelps, as the best on earth, has become a millionaire, a rarity in his sport, but how he has put in the hours. Swimming must be the loneliest sport because the water is a different place. After Spitz retired, it took him a full 17 years before he could go back to the pool for a casual swim.

Perhaps Phelps too will one day regard the end of his water life as a release from some kind of sentence. For now though, it is his stage.

Somewhere out there, a future Michael Phelps is training in isolation, some kid in California or Australia who will, in eight or 12 years be heralded as the new marvel, the latest tomorrow's man. One day, the many records set by Phelps will all be broken.

But for now, Michael Phelps is the future of swimming.

He was recently asked what he thought about as he glided through the pool, going through the motions and putting milliseconds - and light years - between himself and the long line of famous swimming men of the last century, from Duke Kahanamoku to Johnny Weissmuller to Alexander Popov and Ian Thorpe.

"Nothing," he said. "I just get in the water and I swim."