Brazil's Ana Marcela Cunha started her International Swimming Federation (FINA) Marathon Swim World Series title defence with a victory in the first leg in Doha.
Cunha was the overall winner of last year's series and began today with a victory at Doha Cornice in Qatar.
She finished the 10 kilometres race in 2 hours 03min 52.5sec, finishing ahead of newcomer Kareena Lee of Australia, who finished second in 2:3:52.0.
Italy's Rachele Bruni took third place with a time of 2:3:53.0.
Sharon Van Rouwendaal of The Netherlands, the winner of last year's race in Doha, had a disappointing race and finished in 12th place.
Germany's Florian Wellbrock, the European 1,5000 metres champion, won the men's race, recording a time of 1:52:21.6.
In second was Kristof Rasovsky of Hungary in 1:52:22.8, with Jordan Wilimovsky of the United States finishing third in 1:52:24.4.
The next leg of the series is not due to take place until May 12, when the Seychelles host the event.