Spyros Gianniotis, who has an English mother, beat Germany's water king Thomas Lurz, who also booked place at Olympics next summer.
Greek swimming winner will feel at home in London
Spyros Gianniotis, the Greek swimmer, dethroned Thomas Lurz, the German title-holder, to win the 10-kilometre crown at the Shanghai world championships yesterday.
Gianniotis, who has repeatedly lost out to Lurz, the unofficial king of open-water swimming, finally topped the podium after touching in 1hr 54min 24.7sec in baking conditions at Jinshan City Beach.
Gianniotis broke free of a pack after the final turn and passed Lurz and Britain's Daniel Lee Fogg, who had led for most of the race.
Lurz, who is also the three-time defending champion over 5km, took silver just 2.5 seconds behind, with Russia's Sergey Bolshakov placing third.
The top-10 finishers all gained automatic entry to next year's London Olympics - an event that should be something of a homecoming Gianniotis said.
"My mother is English, so the London Olympics is like my home court," Gianniotis told reporters. "I wish I can achieve good result in London."
Gianniotis was delighted with the win after struggling with a right hand injury. "I've trained several years for that. It feels good," he said. "It was very hard these last two months because I had an injury. I tried to never stop swimming and I did it."
Gianniotis, a former long-distance pool swimmer, who won the World Cup 10km in June, said he had experienced problems in the first part of the race, but had managed to overcome them.
"The race for me was like hell to be honest," he said. "I was not feeling so good at five or six [kilometres]. I picked up my pace and at about 9km I felt really good and I said, 'I make my move now'.
"I was hoping I had a bit more than Thomas."
Lurz, a Beijing Olympic bronze medallist and multiple world championship medallist in all open-water events, said he had been nervous on the last lap with Olympic slots up for grabs.
"I tried my utmost. Winning a slot in the London 2012 Olympics is great success to Germany."
Competitors wore high-tech tracking devices during the gruelling event to address safety concerns following the death of America's 2009 10km bronze medallist Fran Crippen during a race in Fujairah last year.