Australian swimmers have set two world records while collecting four of five gold medals on a triumphant opening night at the world championships in Japan.
Ariarne Titmus reclaimed her women's 400 metres freestyle world record, leaving feted rivals in her wake in their Fukuoka final.
And women's 4x100m freestyle relayers - Mollie O'Callaghan, Shayna Jack, Meg Harris and Emma McKeon - bettered the world mark set by Australia at the Tokyo Olympics of 2021 in winning their gold.
Victorious compatriot Sam Short put a golden stamp on his arrival as a 400m freestyle force while Australia's men's relay team - Jack Cartwright, Flynn Southam, Kai Taylor and Kyle Chalmers - also saluted.
Their achievements masked frustration at medal prospect Kaylee McKeown being disqualified in the women's 200m individual medley.
A fearless Titmus said re-capturing her world record was more satisfying than winning Olympic gold in the event in 2021.
In their much hyped race, Titmus blew away American great Katie Ledecky and Canada's 16-year-old sensation Summer McIntosh.
The Australian led from start to finish and clocked three minutes 55.38 seconds, bettering McIntosh's world mark of 3:56.08 set last March.
The trio have all held the world record in the past 18 months - from Ledecky, to Titmus, then McIntosh, and now again to Titmus, who has the word 'fearless' tattooed on her right foot.
"I can see it right before I dive," she said.
"To swim like that and swim really free and fearless, I feel really over the moon to get that one."
In the men's 400m freestyle, Short added his name to a rich Australian list of world champions in the event, including legends Ian Thorpe, Grant Hackett and Kieren Perkins.
"They're my heroes," Short said.
"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 was the fourth-fastest ever while Elijah Winnington finished seventh in his title defence in the race.
Australia's women's relayers clocked three minutes 27.96 seconds, well inside the previous record of 3:29.69.
And in the next race, Australia's men's 4x100m relay team capped a golden night by winning in 3:10.16 ahead of Italy.
In the women's 200m medley semi-finals, McKeown was disqualified for a stroke violation in her transition from backstroke to breastroke - Australia's appeal was rejected - but Jenna Forrester was fourth-quickest qualifier for the final.
In the women's 100m butterfly semi-finals, McKeon and Brianna Throssell qualified for the final fourth and seventh-fastest, respectively.
Australia's Zac Stubblety-Cook was ranked 12th in the men's 100m breaststroke semi-finals and missed a berth in the medal race.
And teammate Brendon Smith placed fifth in a men's 400m individual medley final won by Frenchman Leon Marchand, who broke the longest-standing world record in swimming, eclipsing Michael Phelps' mark in the event at the 2008 Olympics.
