Olympic and world champion Kaylee McKeown dug deep to power home first in the 100m backstroke despite feeling unwell on Tuesday to ensure she will swim the event at the Commonwealth Games.
McKeown touched in 57.77 seconds to finish ahead of rising star Iona Anderson (58.60) who edged her teammate in the morning heats on day two 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 Swimming Championships in Irvine, California in August.
"I feel like I'm 86 years old," said the ailing McKeown, who shares the 10 fastest times in history with American arch-rival and current world record holder Regan Smith.
"But at the end of the day, I think it's important to show that no matter what, you've got to stand up and give it your best. You don't get things given to you in life, so you've got to put it together and see what you can do."
Mollie O'Callaghan, Australia's No 2 sprint backstroker after McKeown, was a no-show despite being the sixth-fastest performer of all-time.
O'Callaghan, who raced the 50m backstroke on Monday and came second to McKeown, will instead focus on the 50-100-200m freestyle.
Sam Short, who blitzed to a world-leading time this year in the 400m freestyle on Monday, was again in the zone over 200m.
He pulled out a personal best in the heats and then bettered it to touch first in 1:45.16 ahead of Kai Taylor (1:45.30).
"It's so fun. It was such a stacked race and I love racing," said Short, who is better-known as a distance swimmer and will defend his 1500m title in Glasgow.
World silver medallist Alex Perkins (25.60) hit the wall first in the women's 50m butterfly while 17-year-old Sienna Toohey (1:05.97) took out the women's 100m breaststroke.
Another 17-year-old, highly-rated prospect Henry Allan, won the men's 100m backstroke in 53.52 while veteran Matt Temple (50.5) was a comfortable winner in the 100m butterfly.