Australia's James Magnussen avenged his defeat at the London 2012 Olympics with victory in the men's 100m freestyle final on Thursday at swimming's world championships.
Magnussen, who was beaten by just one hundredths of a second by Nathan Adrian of the USA in last year's Olympic final, was following up his win in the event at the 2011 world championships.
He clocked 47.71secs, with America's James Feigen at 0.11s back in silver, while Adrian had to settle for bronze this time at 0.13 adrift.
"It was really a tough race. I probably didn't go as quick as I wanted to," said Magnussen, who is nicknamed "the Missile".
"Given the circumstances, I am satisfied with the win."
The only other men to have previously won two straight 100m freestyle world titles are American Matt Biondi, Alexander Popov of Russia and Italian Filippo Magnini.
"That's probably something a bit embarrassing, but I've got a long way to be as good as Popov," said Magnussen when told of the company he is now keeping.
It was Australia's second gold at these world championships after Christian Sprenger won the men's 100m breaststroke final on Monday.
Adrian said he was happy to have had two Americans on the podium and had praise for his Australian rival.
"He's brought an entirely new level to the 100m freestyle. It's a bummer for us, but he's great for the sport," Adrian said of Magnussen.
Adrian said he has plenty in reserve for the 50m freestyle, which starts with Friday morning's heats, the event in which France's Laurent Manaudou is the Olympic champion.
"I went out in 22.3 and that felt like nothing so hopefully that means good things for the 50m tomorrow," said Adrian.
"The first 50 metres were controlled, but I just don't have that second fifty right now.
"I've worked a lot on my speed over the last year, but not so much on my speed endurance, so this next year we'll try to work on that speed coming home."
Feigen, who picked up his second silver after anchoring the USA in Sunday's 4x100m freestyle final, was pleased with his medal at his first major championships.
"I started out at big shaky at this whole worlds thing, but it feels great to get a silver medal," said the 23-year-old.
"I've raced Nathan for a long time so it is great to race alongside him, he's a great teammate and it's great to be on the podium with him."