More than a decade after capturing his first Olympic titles at the 1992 Barcelona Games, Popov has returned to add an improbable new chapter to his story.
On Thursday, he beat Olympic successor Pieter van den Hoogenband and the great Ian Thorpe to regain his 100 metres freestyle title at the world championships.
The beaten Dutchman declared: "He's a legend." For once, the description, so often over-worked, seems to fit.
Through the 1990s and now beyond, the long, lean Popov has extended standards of excellence in freestyle swimming.
His victory on Thursday in 48.42 seconds was the fastest major championship win of his life and made him, at 31, swimming's oldest world champion ever.
It must have been sweet after the defeats of the last few years but there is no talk of revenge.
"Revenge does not exist in my vocabulary. In sport you never talk about revenge. You worry about finishing first, second or third," he said.
"The greatest champions know how to lose as well as win. Losing just makes you tough."
Win or lose, Popov ranks among the very best in the history of his sport.
He won his first senior international title at 19 at the 1991 European championships in Athens and his journey in swimming has taken him all over the world, from his birthplace in Sverdlovsk far away to Australia.
He lived there for 10 years before returning to Europe this year and settling in Switzerland with his wife and two children.
Fittingly he has enjoyed renewed glory in Barcelona, the city where he took the Olympic 50 and 100 metres freestyle titles from the great Matt Biondi.
SECOND PLACE
Two years later, at the 1994 world championships in Rome, Popov won the same two events and consigned a new American challenger, Gary Hall Junior, to second place.
The Russian inflicted the same double fate on Hall at the 1996 Olympics in Atlanta.
Not even the knife of an assailant on a Moscow street a month after his Atlanta triumphs could stop Popov.
One lung and both kidneys were injured when he was stabbed by a melon-seller and he underwent a three-hour operation.
But the following February he was competing again and one year after the attack he was back to his old heights at the European championships in Seville.
Popov had followed his coach Gennadi Touretski to the Australian Institute of Sport in Canberra in January 1993 and it was in Australia that he retained his 100 freestyle title at the 1998 world championships in Perth.
But Perth also witnessed his first defeat in a major championships when his concentration wavered on the starting-block and he was beaten by American Bill Pilczuk in the 50 freestyle.
More defeats lay round the corner when he was ambushed by flying Dutchman Van den Hoogenband at the 1999 European championships in Istanbul, having to settle for silver in the 100 and bronze in the 50.
OLYMPIC REVERSES
Popov bounced back at the 2000 European championships in Helsinki, reclaiming both titles and consigning Van den Hoogenband to silver shortly after breaking the 50 freestyle world mark of American Tom Jager which had stood for 10 years.
But Van den Hoogenband had a bigger mission and at the Sydney Games he took the 100 freestyle title from the Russian.
Popov missed the 2001 world championships in Japan because he was recovering from tonsilitis and the following year he lost again to Van den Hoogenband at the European championships.
He has settled in Switzerland, not too far from Lausanne where the International Olympic Committee and swimming's world governing body FINA are both based. He is on the Athletes' Commissions of both the IOC and FINA.
But, for now, there is still swimming and Popov, defying the years, appears as fast as ever, his competitive appetite undiminished.
