Australian Grant Hackett shattered the men's 800m freestyle world record to take his second gold of the World Swimming Championships on Wednesday.
Hackett now holds a career record 15 world medals
Hackett's time of seven minutes, 38.65 seconds in Montreal lowered the mark of 7:39.16 set by fellow countryman Ian Thorpe at the 2001 championship.
American Larsen Jensen was a distant second in 7:45.63 while Russia's Yuri Prilukov was third in 7:46.64.
Welshman David Davies was sixth, 12.89 seconds behind Hackett in 7:51.54.
Hackett, who also won Sunday's 400m freestyle final, blew the race open early on but said he never felt he could ignore his challengers.
"Even if they're not right beside you, you can feel the pressure of them behind you," he said.
"But I'm just thrilled with that performance."
Hackett said the win was particularly satisfying as it broke Thorpe's record.
"It's always a great feeling to break any world record but to break one of his is special because it has extra credibility," Hackett said.
"I already have the 1500m world record and I thought I really should have the 800m as well because it's in my range, it's really my forte."
As well as competing in the 1500m, his strongest event, the 25-year-old will also turn his attention to racing the 4x200m free relay.
He now holds a record 15 world medals and is already the only swimmer to win gold medals at four world championships.
Also on Wednesday, Germany's Mark Warnecke became the oldest world champion in history when he won the 50m breaststroke final at the age of 35, and Poland's Pawel Korzeniowski won the men's 200m butterfly gold.
Michael Phelps remains on course to challenge Thorpe's record haul of six gold medals at a single world championships by advancing to the finals of the 100m freestyle and 200m medley.
The American has already won two golds in Montreal - in the 4x100m freestyle relay and 200m freestyle.