Tunisia's Ahmed Hafnaoui won the men's 800m freestyle at swimming's world championships on Wednesday.
Hafnaoui came home in a time of 7min, 37.00sec, ahead of Australia's Sam Short on 7:37.76 and American Bobby Finke on 7:38.67.
Hafnaoui, Short and Germany's Lukas Martens were neck-and-neck for almost the entire race until Hafnaoui pulled away over the home straight.
Hafnaoui took silver behind Short in the 400m freestyle on the competition's opening night.
"My last race, the 400, I just keep it in mind and try to go faster in the 800 and take the gold," Hafnaoui said.
Hafnaoui is the reigning Olympic 400m freestyle champion.
Finke, who came into the race as the Olympic and world 800m champion, came through at the end to overtake Martens.