The reign of American swim queen Katie Ledecky is over – at least for now. The five-time Olympic gold medallist was beaten by Australian 20-year-old Ariarne Titmus in the much-anticipated women’s 400m freestyle final at Tokyo 2020, with Games debutant Titmus outlasting her more experienced rival to come within a quarter of a second of a new world record.

When Titmus set the previously-second fastest time in history at the Australian swim trials in June, she delivered a message to her American rival. “Well, she’s not going to have it all her own way I guess,” said the Tasmanian. Those words took on new meaning on Monday.

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The pair’s encounter has been awaited ever since Titmus, then just a teenager, upstaged Ledecky at the 2019 world championships in Korea. It lived up to the hype. Canada’s Summer McIntosh went out strong to touch in first, before Ledecky and Titmus settled into their rhythm at the top of the race. There they remained – Ledecky a body-length ahead of her challenge at the halfway mark.

But Titmus surged in the final 100m. They touched the wall almost together at the last turn and it was on - the defining stretch of this race. Ledecky tried to fight back, but it was in vain. Titmus held on to earn Australia’s second gold medal of this meet, after the weekend’s relay gold.

“It’s surreal,” said Titmus after her win. “I’m over the moon - I’m trying to contain it as much as I can, I’ve got a big program ahead of me, and then I can enjoy this afterwards. I’d prefer to know that I did everything for my other races as well, so I’m trying not to get too excited just yet.”

The Australian was full of praise for her arch rival, who won her first gold medal as a 15-year-old at London 2012 and then dominated the pool at Rio 2016. “I wouldn’t be here without her. She’s set this amazing standard for middle-distance freestyle for girls. If I didn’t have someone like her to chase, I definitely wouldn’t be swimming the way I am.”

Silver medallist Ledecky said that the race had lived up to the hype. “Certainly a tough race,” she said. “I think we delivered. You can’t get much better than that. A tremendous race, a lot of fun, I can’t be too disappointed with that. That was my second best swim ever. If felt like I fought - I fought tooth and nail – and that’s all you can ask for.”

Emma McKeon earlier added an individual 100m butterfly bronze to her Olympic medal haul, touching home third in a thrilling final on Monday morning. Canada’s Maggie MacNeil was the unexpected champion, hitting the wall five one-hundredths of a second ahead of China’s Yufei Zhang.

The stage was set for a blistering final after McKeon – who came to the Games holding the second fastest time in the world this year – qualified third in Sunday’s semi-final behind Yufei and France’s Marie Wattel. The final line-up also boasted reigning champion Sarah Sjöström of Sweden and 18-year-old American Torri Huske – all gold medal contenders.

McKeon had a slow start out of the blocks, touching the lane at the turn in fourth, but recovered with a flying second 50m. As five swimmers all came towards the wall together it was 21-year-old MacNeil who edged ahead to claim gold.

Despite being barely one-tenth of a second away from the gold medal, McKeon was delighted with her effort - a new personal best. Asked whether it was a case of “close but no cigar”, the 27-year-old left no doubt that she was looking at the bright side.

“I think that was a cigar!” McKeon said. “I got an Olympic medal. To do a PB in an Olympic final – I’m pretty happy – you can’t ask for more, that’s the fastest time I have ever swum.”

The morning finals concluded with the men’s 4x100m relay, won comfortably by the United States, a full second clear of the Italians in second, with Australia claiming bronze. Australia were towards the back of the pack for most of the race, touching the wall sixth on the penultimate turn, but Rio gold medallist Kyle Chalmers had a strong final lap to secure a medal.

The action continues on Monday night. The women’s 1500m freestyle event makes its Olympic debut, while Titmus and Ledecky will be back in the pool for their 200m freestyle heats.