Toby Robinson finished a single place outside the medals in the opening leg of the LEN Open Water Cup in Eilat, Israel on Sunday.
The National Centre Loughborough athlete was one of 45 competitors involved in the Men's 10km event.
Robinson ended the race in a time of 1:52:21.46 to finish fourth, less than two-and-a-half seconds adrift of home favourite Matan Roditi, who took bronze.
Russia's Kirill Abrosimov swam clear to take the win - but Robinson was one of four finishers after that to cross the line within five seconds of each other in a tense finale.
In the Women's 10km race, Emily Clarke stopped the clock at 2:07:46.21 to place 17th in her first appearance at the Eilat leg of the Open Water Cup.
Russia took gold and bronze in that one, courtesy of Valeri Ermakova and Mariia Novikova, with Angelica Andre of Portugal splitting them for the silver.
Britain's Nathan Hughes started the men's race but withdrew before the finish.
The Open Water Cup's next event takes place in Barcelona on 4th July.
Remaining LEN Open Water Cup schedule
Barcelona, Spain - 4th July
Istanbul, Turkey - 22nd or 23rd August
Copenhagen, Denmark - 29th August
Paris, France - 5th September
Piombino, Italy - 18th September