Mollie O'Callaghan is on track for back-to-back 100m freestyle world titles after she pipped Olympic champion Emma McKeon in a blanket finish at the world championship trials in Melbourne.
O'Callaghan swam a personal best time of 52.48 seconds to best 11-time Olympic medallist McKeon's 52.52, while Shayna Jack was third in 52.64.
The 19-year-old swam 52.67 to win the world title in Budapest last year and despite eclipsing the mark, was disappointed not to go faster ahead of next month's championships in Fukuoka, Japan.
The time was 0.01 seconds faster than her previous best, set at last year's nationals.
"I'm quite a bit disappointed that I didn't go faster," the Queenslander said.
"I'm very happy I'm on the team for 100 free but I put a lot of pressure on myself
'There's a lot of things I got to work on ... I think next few weeks, I'll have to really work on those things and sharpen them up.
McKeon said it was the quickest she had swam since her Tokyo triumph so felt she was tracking well for the titles and also next year's Olympics in Paris.
"I'm really happy with that," the 29-year-old said.
"I've got my eye set on Paris knowing it was that three-year turnaround so looking towards that I feel like everything's on track.
"I definitely still want to do well at worlds and that's like one of the steps to Paris and I really want to do well there."
In the men's 200m backstroke, Brad Woodward relegated world No.1-ranked Joshua Edwards-Smith to second.
Woodward was the only one under the Swimming Australia qualification time to earn a ticket to Japan.
In the women's 200m breaststroke, winner Abbey Harkin missed the mark by 0.02 of a second.
But after also winning the 100m, although outside the time, she will still make the plane to swim in the medley relay and likely contest the individual events.
