A new Commonwealth record has not been enough to satisfy Ariarne Titmus at the world swimming titles trials in Brisbane.
But the 18-year-old hopes it sets the stage for a mighty tussle with US great Katie Ledecky at next month's world titles in Gwangju, South Korea.
Titmus, 18, appeared to have a dream start to the six-day trials on Sunday night, clocking a scorching three minutes 59.35 seconds to win the 400m freestyle final.
She shaved 0.31 of a second off her own Commonwealth mark to log the second fastest time in the world this year.
Yet Titmus was kicking herself despite finishing almost six seconds ahead of nearest rival Kiah Melverton.
"To be honest I was disappointed with the time," she said.
"I have been training really well and thought I might have a 3:58 in me."
Commonwealth Games champ Titmus hopes to make amends when she lines up against world record holder Ledecky in South Korea.
Olympic champion Ledecky again set the benchmark when she clocked 3:59.28 - the world's fastest time of 2019 - to claim the 400m final at the Santa Clara International Club meet earlier on Sunday.
Titmus didn't sound fazed.
"I will be interested to see how I match up with her in four weeks," Titmus said.
"Hopefully at worlds I can produce something even better."
Meanwhile, Pan Pacs champion Jack McLoughlin upset Olympic gold medallist Mack Horton to claim the 400m freestyle final.
McLoughlin clocked 3.44:34 to claim his world titles ticket while Horton finished second but fell short of the qualifying time.
Young gun Elijah Winnington was third. Only the two finishers book a spot if they also fall under the qualifying time.
Horton now has to rely on making the team in either the 200m or 800m freestyle events this week.
"That 400m final had three of the top six in the world. It was always going to be a dog fight," McLoughlin said.
"But Elijah is a phenomenal swimmer and should be going to worlds - it sucks (he missed out)."
In other results, Emma McKeon booked her ticket when she won the 100m butterfly and backstroke specialist Kaylee McKeown set a huge PB to claim the 200m individual medley final to also get on the plane.
Matt Wilson won the 100m breaststroke but failed to make the qualifying time.
Meanwhile, officials confirmed Olympic silver medallist Madeline Groves had withdrawn from the trials to focus on Tokyo 2020 after recently changing coaches.
