Portugal Colonial - O'Callaghan upsets Titmus to take Australian 200m free title

Titmus, who won the 400m and 800m on Queensland's Gold Coast, was pipped at the post in a stacked field by O'Callaghan, the world champion over 100m who touched in 1:55.15.

Only Canadian star Summer McIntosh and American great Katie Ledecky have gone faster this year.

Shayna Jack was third ahead of backstroke world record holder Kaylee McKeown, who capped an impressive championships that saw her try her hand at different strokes.

"I'm happy with the time but also wish it was a lot faster than it was," said O'Callaghan. "I felt dead in the end, I'm not going to lie. My legs were gone."

In choosing to race freestyle, McKeown opted out of the 200m backstroke after setting a new world record just weeks ago at the New South Wales state championships.

In her absence, 16-year-old Jaclyn Barclay took the honours in 2:11.50 -- a long way outside McKeown's 2:03.14 world best.

Chalmers, who came second to American arch-rival Caeleb Dressel in Tokyo, having won gold at the 2016 Rio Olympics, showed he remains a serious player over the distance.

The 24-year-old touched in 48.00, holding off fast-improving teenagers Kai Taylor -- who won the 200m title -- and Flynn Southam, who came second and third.

"For me, I love team success more than individual success so to have those young kids with me, I think we're really going to do something special next year (at Paris Olympics) in the relay," Chalmers said.

"These young guys are going so well, it inspires me to get out of bed."

Pool queen Emma McKeon, a seven-time Tokyo Olympic medallist, was slated to race the 100m butterfly but opted out, leaving Brianna Throssell to take the title in 57.57.

In other events, Samuel Williamson (27.48) won the 50m breaststroke, while Olympic bronze medallist Brendon Smith claimed the 400m medley crown in 4:16.37.

Australia's top swimmers will be back in the pool in June when they contest the world championship trials in Melbourne ahead of the main event at Japan a month later.

L.Torres--PC