Australia's Olympic champion Cam McEvoy has issued a grim warning to rivals after posting the fastest 50m freestyle time in the world this year.
McEvoy's sustained stretch of excellence continued with victory at Australia's selection trials for the looming world championships.
The 31-year-old clocked 21.30 seconds in Adelaide on Wednesday night - and then declared he can still improve.
"I definitely think I can go faster before the world champs; how much though I'm not sure," McEvoy said.
"But longer term, like more LA (2028 Olympic) levels to the future, I think, yeah, there's a lot more I can improve."
McEvoy, who won last year's Olympic final in 21.25, touched ahead of Kyle Chalmers who set a personal best time of 21.68 at the South Australian Aquatic Centre.
Chalmers is racing in the splash-and-dash purely to improve front-end speed in his pet 100m freestyle, an event he has won Olympic gold and two silvers.
"I had to really trust myself ... just try and stay relaxed in an environment that is a little bit foreign for me," Chalmers said.
"I'm not a 50 swimmer and never really know what's going to happen."
In the women's 200m freestyle, Olympic champion Mollie O'Callaghan triumphed while testing out her new mantra: have fun.
Her plan didn't quite work.
O'Callaghan, who readily admits feeling the crush of expectation, admitted she remained "emotional" and "anxious".
O'Callaghan was Australia's most successful athlete at last year's Olympics with three gold medals plus a silver and bronze.
The 21-year-old then took five months off in a bid to balance her competitive instinct with having fun.
"That's something I'm still learning," she said.
"After the Olympics, I achieved everything I wanted to and I needed that mental recovery after that.
"This year is about having fun but there's been a lot of curve balls thrown at me so it's making it very hard to have fun."
O'Callaghan, who has been battling a knee injury, clocked one minute 54.43 seconds to finish ahead of Lani Pallister (1:54.89).
Also Wednesday night, Sam Short's return to form continued by winning the men's 800m freestyle in 7:40.95.
And in the women's 50m breaststroke, 16-year-old Sienna Toohey again prevailed - a night after earning selection for the worlds by winning the 100m breaststroke.
Toohey won the shorter final in 30.79 seconds, outside the qualifying time for the event set by Swimming Australia.
The Albury schoolgirl shut down social media after her Tuesday night feat when hailed as the future of Australian swimming.
"I saw a bit of it popping up and then I was like: 'Oh, I can't get too full of myself' so I put my phone on 'do not disturb'," Toohey said.
Former talented cross country runner Harry Turner won the men's 200m butterfly in 1:54.90 to secure selection for the world titles in Singapore from July 27-August 3.
Nash Wilkes won the men's 50m breaststroke in 27.52, outside Swimming Australia's automatic qualifying time for the worlds.
