Hector Pardoe won Great Britain's first 10km open water World Championship medal for 13 years with bronze in Qatar.
It also secured a third Olympic quota place for Team GB in the event at this summer's Paris Games.
The 22-year-old is the first Briton to win a medal in the event since Kerri-Anne Payne's gold in 2011.
Pardoe, who needed a top-15 finish to secure an Olympic place, claimed bronze in the final few strokes in Doha.
"I just wanted to secure the Olympic qualification, so to come out with a medal is even better," said Pardoe, who competed at the Tokyo Games in 2021.
"The emotions were quite high, following the path of redemption from Tokyo with the eye injury," said Pardoe.
"I was feeling great throughout the whole race (in Doha), and that last lap I made it happen and followed my strategy perfectly.
"I went into Tokyo as a 20-year-old without much experience. The experience I've gained in the last three years will really set me up nicely to compete with the big boys in Paris."
Behind Pardoe, there was further good news for Team GB as Tobias Robinson finished 15th to claim the last Olympic quota spot in the event, while on Saturday, Leah Crisp secured a quota place with her 17th place in the women's event.
Elsewhere, there was disappointment for Jack Laugher and Anthony Harding as the pair came fifth in the men's 3m synchronised diving.
The duo, who have already guaranteed their Olympic quota spot in Paris, have won two World Championship silvers, Commonwealth gold and two Diving World Cup silvers during their 18 months competing together.
Also on Sunday, GB's women's water polo team lost 22-10 to Italy in their first World Championships match since 2013.
The team will play Canada in Group D at 09:00 GMT on Tuesday.