When Muhammad Ali was at the peak of his powers a sparring partner dreamt he had beaten him and then woke up and rushed to apologise.
It is getting like that here this week, with the supreme swimmer Michael Phelps, who this morning was poised, with what can only be described as colossal certainty, to become the greatest Olympian of all time by winning his 10th gold medal in the final of the 200 metres butterfly.
He won his ninth – his third of these 29th Olympics and in still another world record time – yesterday when simply annexing the 200m freestyle, a performance so withering in the awe-struck Water Cube that what might indeed be described as the Ali syndrome received its first official expression.
The silver medallist Park Tae Hwan, two seconds behind the 23-year-old American from Baltimore who at 1:42.96 was shaving nearly a second off his own record, sighed, massively, and said: "I said I would beat him before the race but I was just saying that, I felt I had to make that statement as a competitor, but I never believed it. When he goes into the water he is just a man on his own, separate from everyone."
The South Korean, representing a nation famous for the ferocious edge it brings to every battle on and off the sports field, added: "The truth is that is an honour to be in the same final as this man."
Even Phelps, notorious for his routine dismissals of the meaning of what he does, and its place in history – "hey, I've always been good in the water, it's what I happen to do" – seems at last to be touched by the huge and still growing scale of his achievement.
Yes, he admitted, he was aware – and very proud – of the fact that yesterday's victory took him into the pantheon of Olympic sport, joining Carl Lewis, Paavo Nurmi, Larysa Latynina and Mark Spitz on the golden mark of nine.
"I haven't talked here about breaking Mark's record gold medals in the Munich Olympics [seven] because I'm not yet halfway there. I've got to do my work and my recoveries, and there are so many factors to consider, but this other thing, being so close to winning more gold medals than anyone in history, well, it's a little bit mind-blowing.
"I've spent some time with Carl Lewis and I've had a few words with Mark, and I've begun to learn what this means. If it happens, well, it will be unbelievable."
Prepare, then, for the greatest burst of sporting incredulity since Ali, a notable Olympian himself who won gold in Rome in 1960, ransacked another Olympic champion, George Foreman, in Kinshasa in 1974. It is going to happen, barring absolute misadventure, or the most freakish circumstance, because here yesterday Phelps stroked his way with immense power, even beauty, beyond the sneer that even the highest level of swimming is no more than a disturbance in the water. The disturbance created by the American was not so much in the water, which offers him such minimal resistance, but in the hearts of his opponents.
As the sun pierces the haze here this morning Phelps will still be in the company of the phenomenal Nurmi, the Flying Finn, the steely but also exquisite former ballet dancer-turned-gymnast Latynina, the virtuoso sprinter and long jumper Lewis, and the extrovert Spitz, with whom Phelps shares only a miraculous ability to part the water.
Then, it is perverse to believe otherwise, he will be on his own. The champion who in his youth was terribly mocked for his big ears – his mother was recently discussing this trauma of her fiercely private son – will be inhabiting ground in sport known only to him.
He will leave behind the most astonishing deeds ever achieved in Olympic sport. They are worth recalling as the defining background to what Phelps is now making of an already extraordinary career.
The great Nurmi set world records at every distance between 1500m and 20 kilometres. His gold medals came in Antwerp, Paris and Amsterdam between 1920 and 1928. In Paris he took the 1500m and 5,000m gold – with a gap of just 26 minutes between the races. Barred from competing in Los Angeles in 1932 – because of claims that he had had the temerity to receive money for what he did so peerlessly – he went home to Finland in a huff and promptly broke the 5,000m world record, which stood for nearly 13 years.
Latynina experienced famine and war in her native Ukraine before winning every gymnastic discipline between 1956 and 1964 in Melbourne, Rome and Tokyo and declared: "I learnt a very difficult truth in my difficult childhood. Good never comes on a silver platter while talent is primarily perseverance and hard work."
Spitz and Lewis were extraordinary Americans before they became icons. Spitz, who won two of his gold medals in relays in Mexico City in 1968, was outspoken and brash and proud of being Jewish, and provoked much scorn with his failed claim that he would win six gold medals in Mexico, a fact which he turned sharply against his critics when he went one better than that in Munich. Lewis also took on some American prejudice when he refused to conform to athletic stereotypes, to the point of painting his nails.
His crushing riposte to his critics came with the medals accumulated from 1984 to 1996 in Los Angeles, Seoul, Barcelona and Atlanta.
In many ways Phelps is an unlikely candidate to outstrip this supremely confident Gang of Four. Reclusive, deadpan, he doesn't make a drama of what he does and it was the rarest of emotion he displayed this week when his 32-year-old team-mate Jason Lezak rescued America – and Phelps' goal of eight medals here – in Monday's last-touch victory over France in the 4x100m freestyle.
Phelps had never been more demonstrative in public than when Lezak overhauled the world record holder Alain Bernard over the last 50 metres. Twenty-four hours later he was still sweating out the emotion. He said: "When I saw Bernard with a full body length lead I thought, 'That's it,' but when Jason did it, I just thought, 'Wow, that shows anything is possible."
Are eight gold medals possible here? "There is only one way I can go... it is to take each race as it comes, and then make sure I get the best possible rest. I was very pleased today. I just wanted to be out on my own, which I was by the 100-metre mark. I was out in open water, and I was in the middle [his draw in lane six after doing the mere necessities in the heats], which makes it difficult for the other guys to see me. I knew Park would have a strong last 50 metres, so I had to keep my focus and my concentration."
He did it with overwhelming conviction, leading from first to last and then raising his arm in the air and smiling with the kind of pleasure that he often tends to disguise. "Just because I don't talk about my goals, it doesn't mean I don't have them – or that I want to achieve them very badly," he said the other day.
The origins of his motivation have never been much expressed, but according to both his coach and his mother they are as intense as those of any athlete at the Olympics.
His mother, Debbie, suggests the water was one refuge from the taunting he received as a boy. She remembers how he emerged from a school swim meeting in tears. Two members of the opposing team had baited him relentlessly about the size of his ears.
Some years later, when he had qualified for the Sydney Olympics, one of them came to congratulate him. He was cut dead when he said, "Remember me? I swam against you". Phelps replied, "I don't seem to recall who you are.' His mother reports that he knew well enough and his coach, Bob Bowman, says, "You might not think it, but everything that comes up Michael uses for motivation – and look where it's taken him."
Yesterday it was another podium ceremony, the playing of the American national anthem, and a brisk walk to the semi-final of the 200m butterfly. He won it so easily he seemed to fill every corner of the pool.
It is what everyone now expects from the man who owns the 29th Olympics.
Four Niners: The athletes whose gold medal tally Phelps is set to beat
Born: 13 June 1897, Turku, Finland. Died: 2 October 1973.
The "Flying Finn" won nine golds and three silvers in the 1920, 1924 and 1928 Games, making him track and field's most bemedalled athlete. He might have added more in 1932 but was banned because he had received payment for running and was thus deemed a professional.
Born: 27 December 1934, Kherson, Ukraine.
Represented the Soviet Union in gymnastics in 1956, 1960 and 1964, winning nine gold medals as well as five silver and four bronze. She won a medal in every event in which she took part, and her total of 18 makes her the most successful competitor in Olympic history.
Born: 10 February 1950, Modesto, California.
Having made his mark in Mexico in 1968, when he won two gold medals, a silver and a bronze, four years later the American freestyle and butterfly specialist went to town, winning seven golds – a record at any one Games.
Born: 1 July 1961, Birmingham, Alabama.
Won his nine golds – and one silver – in 1984, 1988, 1992 and 1996 in the 100m, 200m, long jump and 4x100m relay. His duel with Ben Johnson in the 1988 100m final was perhaps the biggest Olympic story of all time.