World record holder Kaylee McKeown clocked the fastest 50m women's backstroke of the year on Monday as she warms up for the Commonwealth Games while Sam Short swam a blistering 400m freestyle.
McKeown touched in 27.13 seconds to edge 200m freestyle world champion Mollie O'Callaghan (27:19) on day one of the Australian trials in Sydney.
The six-day event acts as qualifying for not just next month's Glasgow Commonwealth Games but also the Pan Pacific Championships in Irvine, California a month later.
"It's good to come out tonight and get a 50 under my belt and be pushed along the way," said McKeown, the most dominant female backstroker in the world.
The Olympic 100m and 200m backstroke champion will also suit up for those events in Sydney.
But she pulled out of the 200m medley, where she boasts the sixth fastest time ever, citing illness.
In her absence, Jenna Forrester (2:09.07) touched first ahead of the fast-improving Ella Ramsay.
Short was on fire, under world record pace until tiring over the final 50m.
He hit the wall in a personal best 3:40.67 – the 10th quickest of all time and just outside German Olympic champion Lukas Martens' 3:39.96 world record set last year.
Olympic silver medallist Elijah Winnington came second, nearly four seconds behind.
"Jeez, that hurt so much," said Short. "I've got all the confidence right now, I feel like I'm invincible, so I went out there and gave it a red hot crack."
Lani Pallister dipped under four minutes in the women's 400m freestyle, powering home in 3:59.72.
She is one of only an elite few to breach the barrier that also includes Canada's Summer McIntosh, American great Katie Ledecky and recently retired Australian Ariarne Titmus.
Pallister has been in sensational recent form, setting lifetime bests across the 400-800-1500m board as she steps up to fill the void left by esteemed teammate Titmus.
Her training partner Forrester came second after backing up from the medley.
"I would have liked to be a little bit faster, so sorry for my profanities when I touched the wall," said Pallister.
Sam Williamson (59.07) clocked the best time in the men's 100m breaststroke as he returns from a career-threatening injury, while Issac Cooper (24.46) won the men's 50m backstroke.