Keri-Anne Payne, of Britain, added the world 10km marathon crown to her Olympic silver medal on a blistering morning at sea off the Italian coast at Ostia near Rome today.
The 21-year-old, coached by Sean Kelly at Stockport, led the race from start to finish and won in 2hrs 1min 37.1sec, five strokes clear of the fingernail fight for silver, which went to Russia's Ekatarina Seliverstova ahead of Italy's Martina Grimaldi.
Payne's first world title gave Britain its second gold in 24 hours at the 13th world championships, after 15-year-old diver Tom daley lifted the 10m platform title at the Foro Italico Olympic complex in Rome.
The British team tactic of "getting out front and staying clear of the fight" paid off in spades half way through the race: by then, Payne's fast pace had burned off Olympic champion and five-times world champion Larisa Ilchenko, of Russia, who hailed a boat and left the race.
Unable to defend her crown, Ilchenko, downcast and tearful, talked of the effects of having raced to silver in the 5km race the day before. Rumours suggested that she had arrived at the championships with a leg injury. However, the thrust of Russian media reports was that Ilchenko had complained that while she had donned a textile suit because of the heat of the day, others were wearing "speedboat suits" in which compression factors played a key part in the result.
Payne, who wore what she wore to take silver in Beijing last year - the LZR - said that it felt "amazing to win" her first world crown at the end of a post-Olympic season that has seen her concentrate on speed in the race pool for the 200m and 400m medley events she will race at the Foro Italico from Sunday.
The only reason that Payne was in the 10km race at Ostia was to chase the money needed to pay her way to the London 2012 Games: "It was a funding issue. We were three-quarters way through the season when we thought we had to think about freestyle."
Payne was unaware of Ilchenko's withdrawal until told about it by the media. It was a bitter-sweet. She had wanted to beat the Russian in a tight finish to reverse the excrutiating order of things in Beijing a year ago, when Ilchenko pipped Payne and teammate Cassie Patten, the bronze medallist absent from Ostias because a stomach virus had kept her from racing well at trials earlier in the year.
Ilchenko lined up bidding for a fourth successive 10km title. After she withdrew, the threat came from Grimaldi and winner of the 5km ahead of the Russian yesterday, Melissa Gorman, of Australia.
Grimaldi drew level with Payne just before the final buoy of the four-lap circuit at sea but the Olympic silver medallist took the inside track closest to the buoy, handled what was almost a 360-degree with brilliant efficiency and emerged a body length ahead of rivals. "I could see her when she drew up but I didn't want to sprint at that stage, so I just kept up the same pace going into the turn," said Payne.
Into the final sprint for home, there was never a moment when it looked as though Payne might waver. The gold was hers 300m out from home, though Seliverstova and Grimaldi were never more than a 1m from her feet.
Payne went from the beach straight to an ice bath before donning constriction clothing that she will wear for the next three days when not swimming. The aim to help her body to recover in time for the 200m medley in the pool on Sunday.
As to not having focussed on open water all season, Payne replied: "I was pretty confident in my fitness. You don't go from an Olympic silver medallist to a bad swimmer overnight."
Kelly, her coach, added: "We've done a lot more speed work this season and she hasn't put in as many metres [in training] as she did last year. But she's got a huge backlog of work to rely on."
Payne praised Italian organisers for turning around what looked like a disaster scene last weekend after storms caused euros 100,000 of damage to the event infrastructure at Ostia. "They have done a magnificent job. It's the best open water structure and event I've ever been to."