American Marconi Wireless News - O'Callaghan and Short star at Australian swim trials

Australia's women are a global powerhouse over the sprint distance with huge depth in their ranks, making a spot on the team for major events ultra-competitive.

Olympic 200m freestyle gold medallist O'Callaghan, as expected, touched first in 52.33 with 50m freestyle world champion Harris (52.63) second.

Shayna Jack came third and Alex Perkins fourth, with all four set be part of their formidable relay team which has been a dominant force for more than a decade.

Australia is the current Olympic and world 4x100m champions.

"Pretty stoked to come here and race and have the opportunity to race against Meggie and the other girls, and they definitely get the best out of me," said O'Callaghan.

The six-day trials, which culminate on Saturday, act as qualifying for not just next month's Glasgow Commonwealth Games but also the August Pan Pacific Championships in Irvine, California.

Short has been in electric form all week and surged to victory in the 1500m freestyle in 14:42.09. He was under world record pace for the first 1,000 metres before tiring.

"That hurt so bad. The last 500 I was just thinking about getting take out after the race was done, to be honest," said Short.

"I was like, 'Oh no, just keep going. Get to the end'."

The 22-year-old had already powered to the quickest 800m freestyle since 2009 when world-leading times were set in the now banned "supersuit" era.

He also clocked a personal best, and 10th quickest of all time, in the 400m freestyle and convincingly won the 200m.

Tokyo Olympic champion and former world record holder Zac Stubblety-Cook was explosive in the final 50m to take out the men's 200m breaststroke in 2:08.92 ahead of Bailey Lello.

"It's the most nervous I've been for a little while... I just had a job to do and got the job done," said Stubblety-Cook. "I'm very grateful for that field pushing me along there."

In the women's 200m breaststroke, Ella Ramsay went out hard and qualified fastest in 2:24.04 with Tara Kinder a fingertip behind.

Se-Bom Lee executed perfectly to hit the wall first in the men's 200m backstroke in 1:56.75.

L.Mason--AMWN