Kaylee McKeown's first swim of the Tokyo Games has resulted in a new Olympic record for the 100m backstroke.
In a ferocious period in the pool, the previous mark was broken in three consecutive heats, with Canada's Kylie Masse clocking 58.17 seconds, before American Regan Smith lowered the record to 57.96.
But neither was any match for McKeown, who stopped the clock in 57.88 seconds, to qualify fastest for the semi finals. It's shaping up as an epic battle between the trio for the gold medal, with the semi finals to take place on Monday, before Tuesday's final.
Fellow Australian Emily Seebohm also comfortably qualified, setting the fifth fastest time of 58.86.
Kyle Chalmers was also in action in the 4x100 freestyle relay, and the 23-year-old delivered a sensational time of 46.63, one of the top-10 splits in history.
Swimming behind Cameron McEvoy (49.18), Zac Incerti (47.64) and Alexander Graham (48.44), Chalmers nearly hauled in the United States team, but ultimately settled for second in the heat.
Australia has qualified third fastest overall in 3:11.89, behind Italy (3:10.29) and the United States (3:11.33).
Elsewhere, Queensland teenager Tommy Neill is through to the semi finals of the 200m freestyle, qualifying eighth fastest in a time of 1:45.81.
The news wasn't so good, however, for Elijah Winnington, who missed the semi finals after setting the 22nd fastest time.
In the women's 100m breaststroke, 20-year-old Queenslander Chelsea Hodges advanced to the semi finals with a time of 1:06.70, the 12th fastest overall, although Jessica Hanson (20th) missed out.
And both Mitch Larkin (4th fastest) and 17-year-old Isaac Cooper (13th) qualified for the semi finals of the men's 100m backstroke.
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