David Davies dug deep to claim a second swimming bronze medal for Great Britain in the men's 1500m freestyle in Athens.
The 19-year-old smashed the British and European records, clocking 14 minutes 45.90 seconds to add to Steve Parry's 200m butterfly bronze.
Australian Grant Hackett successfully defended his Olympic crown in a new Olympic record time of 14:43.40.
American Larsen Jensen took the silver medal after a tough fight with Hackett, who remains unbeaten since 1997.
Davies moved up into second place at the 550m mark before he was eventually overpowered by Jensen 400m later.
The Welshman knocked a massive 12 seconds off his personal best as he battled to bronze.
Only three swimmers have ever gone faster over the gruelling distance - Hackett, Jensen and former world record holder Kieren Perkins.
"It's unbelievable," Davies told BBC Sport. "I'm shocked but really delighted.
"I said to my coach beforehand 'If I drop dead during the race just come and fish me out'.
"I wanted to give it my all and I gave it everything."
Fellow Briton Graeme Smith was up with the early pace but eventually finished
sixth in 15:09.71.
"The 1500m is very punishing," Smith told BBC Sport. "I think my bones are getting too old now and this could be my last one."
Hackett powered his way into a lead of a body length and a half at the first turn and made it clear he would set the tempo of the race.
But Jensen began to close on the 24-year-old with 300m left to swim and Hackett had to find a final kick to win the most gruelling race of the Games.