The greatest Olympian in history brought down the curtain on his uniquely glittering career, and the London 2012 swimming competition, by doing what has come naturally for over a decade – winning.

Swimming the third leg for the United States in the 4x100 metres medley relay – an event they have never lost at any Olympic Games – Michael Phelps (pictured top) devoured the lead established by another all-time great swimmer, Kosuke Katajima of Japan, in the breaststroke phase and powered to the head of the field with his instantly recognisable, pterodactyl-like butterfly.

Freestyler Nathan Adrian was quick to exploit the edge that the great man had given him and saw the team home the best part of two seconds clear, in a time of 3min 29.35sec.

The win put the seal on what has been as fantastic a Games in the pool for Phelps' country as it has been disappointing for their old arch-rivals, Australia.

With only the open-water events in Hyde Park to come, the Americans have racked up a total of 30 medals, more than half of them gold, to the Australians' 10, which includes just one solitary gold.

Underlining the US' dominance is the multi-medal hauls of their top swimmers.

If Phelps led the way with four golds and two silver medals – some way short of his epochal eight gold-medal haul four years ago in Beijing – his team-mates were not far behind him.

Team-mate and rival Ryan Lochte managed five medals at London 2012, as – following the US women's team's scorching win tonight in their 4x100m medley relay in a world record 3:52.05 – did Allison Schmitt and Missy Franklin.

Franklin, a 17-year-old 6ft 1in backstroke specialist, actually matched Phelps' total of four gold medals and, should she be granted the great man's competitive longevity, might conceivably one day challenge his towering overall total of 22 medals – 18 of them gold.

"I'm definitely just taking them one at a time," she said after the night's events, betraying the sort of level-headedness likely to stand her in good stead in her years as a sporting celebrity.

There was a world record, too, in the men's 1,500m – the longest event in the Olympic pool – with Sun Yang of China smashing his own mark by more than three seconds in recording a time of 14:31.02.

It was this remarkably versatile swimmer's fourth medal of the Games, following gold in the 400m, silver in the 200m freestyle and bronze in the 4x200m freestyle relay.

He afterwards drew applause from journalists by offering an aggressive response when questioned over allegations of doping that have swirled around the Chinese swimmers, following their strong performance in London, including five golds.

"I think many people think China's gold medals are because of doping or other substances," Yang said.

"I can tell you it's thanks to hard work – training and hard work.

"Chinese are not weaker than the US or other countries."

In the other event in an extraordinary night's swimming, Ranomi Kromowidjojo of the Netherlands completed a sprint double in the women's 50m freestyle.

Tonight, though, was all about Phelps, this phenomenon who first took to an Olympic pool in Sydney 12 years ago, managing fifth place in the 200m butterfly.

Now 27, he has amassed a haul of Olympic gold worthy of a central bank and was this evening presented with a striking silver trophy proclaiming him "The Greatest Olympic Athlete of All Time".

It is just a pity that he had to collect the trophy in a pair of those ghastly lime-green trainers that appears to be part of the US swim team's gear.
Not that the great man seemed to mind, as he flashed his trademark toothy grin to all corners of the London Aquatics Centre.

Phelps, whose London 2012 campaign had begun in low-key manner with fourth place in a 400m individual medley won in emphatic style by Lochte, used the post-race media formalities to confirm that he would be retiring.

"I told myself I never want to swim when I'm 30," he explained.

"That would be in three years."

Furthermore: "I have been able to do everything I wanted.

I have been able to do something no-one else has ever done."

Looking at his new trophy, he reflected that it was "kind of weird looking at this thing and seeing 'The Greatest Olympic Athlete of All Time'".

He had "looked up to Michael Jordan all my life" because, he said, he was the greatest basketball player of all time.

Now "I have been able to become the best swimmer of all time".

Phelps, though, has always been more eloquent in the pool than with a microphone and it was the precocious Franklin who produced the best epitaph for his extraordinary career.

"Just watching Michael swim is beautiful," she said.

Those of us privileged enough to have seen him will never forget the experience.

By David Owen at the Aquatics Centre on the Olympic Park in London