The third round of nine in the International Swimming Federation (FINA) Marathon Swim World Series is set to take place in Setubal, Portugal this weekend.
The world open water swimming competition sees athletes complete a 10km course.
Leading the pack in the women's event is Brazil's world champion Ana Marcela Cunha, who was victorious in the opening race in Qatar in February.
However she was pipped for top spot in the Seychelles last time out after a thrilling duel with Italy's Ariana Bridi.
The men's field is wide open, with Germany's Florian Wellbrock and Marc-Antoine Olivier of Canada aiming to repeat their successes in Qatar and Seychelles, respectively.
One to watch is Hungary's Kristof Rasovszky, who has been on the podium in both races in the series – second in Qatar, third in Seychelles.
Setubal is part one of two in an European leg of the tour, with the next event taking place in Balatonfured in Hungary on June 15.
The series will then cross the Atlantic for two stops in Canada, before returning to Europe and a race in Ohrid, North Macedonia,
The final two rounds of the series are set to take place in Asia, in Nantou, Chinese Taipei and Chun'an, China.
The races start at 4pm local time in Setubal on Saturday.