Daniel Fogg has finished fifth in the open water men's 10km swim in the Serpentine.
The race was won by Tunisia's Oussama Mellouli, who took bronze in the 1,500m freestyle in the pool last week, ahead of Germany's Thomas Lurz who took silver and bronze medallist Richard Weinberger of Canada.
The 24-year-old Fogg was 15th at last year's World Championships in the boiling water off Jinshan City Beach in Shanghai.
In Friday's race, Fogg was third after the first lap but at one point dropped to joint 22nd.
Sixteenth at the end of the fifth lap, the Kevin Renshaw-trained swimmer hauled himself up to a highly-respectable fifth place.