Australia’s Ariarne Titmus has reclaimed the women’s 400 metres freestyle world record with a stunning victory at the world championships in Japan.

Titmus emphatically blew away feted rivals Summer McIntosh from Canada and American great Katie Ledecky to triumph in Sunday night’s hyped final in Fukuoka.

The Australian clocked three minutes 55.38 seconds, bettering McIntosh’s world mark of 3:56.08 set last March.

“I was really excited for this race … Katie and Summer always put up a great fight,” said Titmus, who held the benchmark time for 18 months before McIntosh’s March feat.

“It’s just great to be a part of it.”

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Leading from start to finish, Titmus touched the wall an emphatic 3.35 seconds ahead of Ledecky, with 16-year-old McIntosh third some 4.21 seconds off the pace.

The trio have all held the world record in the past 18 months – from Ledecky, to Titmus, then McIntosh, and now Titmus again.

“It’s probably my most satisfying win,” said Titmus, the Olympic champion in the event.

“To swim like that and swim really free and fearless, I feel really over the moon to get that one.”

Titmus has the word ‘fearless’ tattooed on a foot.

“I can see it right before I dive,” she said.

“(I was) just trying to swim like that little girl that I was when I was first up against Katie. I was never afraid to take it to her.

“And Summer and Katie are world record holders so I feel like the only way to beat them was to try and take it out and see who had the most fight and the most left in the tank at the end.

“And it worked.”

Short joins his heroes

Earlier, Australia’s Sam Short put a golden stamp on his arrival as a swimming force, winning the men’s 400m freestyle.

Short adds his name to a rich Australian history in the 400m freestyle featuring legends Ian Thorpe, Grant Hackett and Kieren Perkins.

“They’re my heroes,” Short said.

“They are some of Australia’s best athletes ever. It’s an honour to be with them.

“And hopefully I can continue to move forward and one day rival Thorpey in the rankings.”

The 19-year-old Short, the youngest swimmer in Sunday night’s final, pipped Olympic champion Ahmed Hafnaoui by 0.02 seconds.

Short led at every 100m mark before the Tunisian challenged in the last 50m.

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“I knew he won that sprint finish in Tokyo – he’s a big guy, I could see him coming at me that last 100,” Short said.

“And that last 25, I threw everything at the wall.

“I am stoked. I couldn’t wait to get on the lane rope and start flexing, to be honest.

“It’s what you dream about as a young guy.”

Short’s winning time of 3:40.68 is the fourth-fastest ever and just 0.61 seconds outside of German great Paul Biedermann’s world record set 14 years ago.

-AAP