Mollie O'Callaghan anchored Australia to glory in the women's 4x200m freestyle relay on Thursday night and in doing so won a record-equalling 11th long-course world championship gold medal.
The only other Australian who owns 11 long-course world championship gold medals is Ian Thorpe.
An Australian quartet featuring Lani Pallister, Jamie Perkins, Brittany Castelluzzo and O'Callaghan, who swam in that order, seized gold at the swimming world championships in Singapore with a time of seven minutes, 39.35 seconds (7:39.35).
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The United States picked up silver in 7:40.01 as China claimed bronze in 7:42.99.
Crucial to Australia's win was a phenomenal third leg by Castelluzzo. Australia was placed second when the Adelaide product began her leg, and she found herself trailing by more than a full body length as the United States' Erin Gemmell surged ahead at a rate of knots, but Castelluzzo mowed the American down in the final 50 metres to ensure O'Callaghan started her anchor leg with the team leading.
Watch the World Aquatics Championships live and free on Nine and 9Now.
O'Callaghan was up against the greatest female swimmer of all time, American icon Katie Ledecky. The champion from Logan began her swim with an advantage of 0.39 of a second, and although it was clear she was tired having already swum her 100m freestyle heat and semi-final earlier in the day, she held off the legendary American to ensure victory for what was a new-look team.
This was a team missing Ariarne Titmus and Brianna Throssell, both of whom featured in Australia's 4x200m freestyle triumphs at the Paris 2024 Olympics and the 2023 world championships in Fukuoka. Throssell called time on her decorated career after the Paris Games, while Titmus is having a 12-month break post-Olympics.
Titmus commentated on Thursday night's relay win, sharing her astute thoughts as the Dolphins in the pool filled her with pride.
"Well done, Team Australia," Titmus said on the Nine coverage as O'Callaghan closed out victory.
"Two women in that race that have never swum in a relay final [on a senior Dolphins team], and we are still on top of the world."
O'Callaghan won the 200m freestyle final on Wednesday night to draw level with Grant Hackett on 10 long-course world championship gold medals, before surpassing Hackett and matching Thorpe on Thursday night.
The 21-year-old has now won three gold medals at these world titles — in the 4x100m freestyle relay, the 200m freestyle and the 4x200m freestyle relay — and could yet add to her stash this week with the 100m freestyle and more relays to come.
"It's everything to me," O'Callaghan said of winning another relay gold medal in an interview on Nine.
"I take any opportunity to come and do this event.
"I knew I had to lift for this. I'm always here for the relays.
"It's a great privilege because it shows the depth that we have. It just shows the depth coming through to LA [the 2028 Olympics], and to start off like this is just incredible."
And what does it mean to O'Callaghan to be sharing that record with Thorpe?
"I know this has been the hot topic of the week," the Queenslander laughed.
"Actually, I haven't really thought about it too much.
"Coming off [the] Olympics last year and having the downs of the break and the post-Olympics blues and then injuring myself, it's just been a rollercoaster.
"And to come along here and to compete in the finals [and] to get golds is just something I wouldn't believe at the start of the year, or last year."
Bronze for Chalmers
Earlier in the night, Kyle Chalmers secured bronze in the men's 100m freestyle with a time of 47.17 seconds.
Romanian superstar David Popovici clinched gold in 46.51 — a European and world championship record — as American Jack Alexy claimed silver in 46.92.
Pan Zhanle, the Chinese sensation who won gold in the event at the Paris Olympics and broke the world record in doing so, crashed out in the semi-finals in Singapore.
McIntosh keeps astonishing bid alive
Meanwhile, 18-year-old Canadian sensation Summer McIntosh kept alive her incredible pursuit to win five individual gold medals at these world titles by triumphing in the women's 200m butterfly, which she won with a world championship record of 2:01.99.
McIntosh finished just 0.18 of a second outside the world record — the 2:01.81 set by China's Zige Liu in 2009 during the controversial "super suit" era.
McIntosh must now win the 800m freestyle and the 400m individual medley if she is to become just the second swimmer in history to claim five solo gold medals at a single long-course world championships.
She will have to overcome Ledecky in the 800m freestyle, the American legend's pet event, to achieve the remarkable feat.
Australia's Elizabeth Dekkers netted bronze in the 200m butterfly in 2:06.12.
Silver was won by American Regan Smith in 2:04.99.
