Sprint star Cate Campbell fired a warning shot with a lightning-fast 50m freestyle swim to win the Australian title Sunday as Kyle Chalmers sealed the men's treble.
Campbell, the top-ranked woman in the world so far this year, touched in 24.28secs ahead of fellow Tokyo Olympic medal prospects Emma McKeon (24.39) -- who edged Campbell to win the 100m -- and sister Bronte (24.75).
"It's a little bit of a change up going finals in the morning, but I'm a veteran of the sport and that has to count for something," said the 28-year-old, who is targeting a fourth Olympics.
Finals at Australia's national championships on the Gold Coast have been swum in the morning, mimicking the schedule in Japan where heats will be in the evening.
The last Olympics that followed the format was Beijing in 2008 where Campbell won a bronze in the 50 -- one of the few swimmers still competing to experience the concept at a Games.
"It really does come down to mindset when I remember all the way back to 2008. You just need to be able to stand up and race when it counts," she said.
Campbell, who finished fifth at the 2016 Rio Olympics, holds the Commonwealth and Australian record of 23.78, fractionally outside Sarah Sjostrom's world mark of 23.67.
The Swedish great is set to be a key rival again in Tokyo, although her preparations suffered a setback in February when she broke her right elbow after slipping on ice.
Australia's Olympics trials are in June.
Rio Olympic champion Chalmers, who is on the comeback from shoulder surgery, had already won the 100m and 200m freestyle and added the 50 crown when he touched in 22.30.
"I've managed to go faster in the morning in the finals (from the heats) so that's all that matters," he said.
Elsewhere, Ariarne Titmus won the 800m title in 8:23.13, some 10 seconds slower than American great Katie Ledecky swam last month.
"That one hurt more than I remember," said the 20-year-old, the 400m world champion. "The time is not great, but I was happy to hang on."
World championship silver medallist Matt Wilson was upset in the 200m breaststroke, with Zac Stubblety-Cook taking the title in 2:08.28.
Wilson was leading through 150m but Stubblety-Cook, who also won the 100m title, powered back to touch first.
"Both of us will be pretty happy with that swim considering the time of the season," said Stubblety-Cook.
Abbey Harkin (2:25.26) took out the women's 200m breaststroke title.