Australian sprint stars Eamon Sullivan and Libby Trickett reclaimed their crowns as the fastest swimmers in the world, scorching the Olympic trials with a pair of freestyle world records.

Sullivan reasserted his dominance with a world record in the 50m freestyle and Trickett followed up an hour later by becoming the first woman to legally break 53 seconds in the 100m freestyle, clocking 52.88s to slash 0.42s off German Britta Steffen's record.

For Sullivan it was a case of third time lucky after twice missing the 100m record on Tuesday and Wednesday evening.

Trickett reclaimed something which was she felt was rightfully hers after FINA officials failed to ratify her previous best time of 52.99s because she was racing superfish Michael Phelps in this pool just under a year to the day.

The decision cost Trickett $20,000 in prizemoney, but the 23-year-old doesn't care anymore.

"I cannot say how much I wanted to do that," said Trickett, who punched the air in joy after touching the wall.

"Ever since Duel in the Pool last year ... I've just wanted it so badly and to see it officially up there is just amazing.

"With all the talk about me dragging off Michael Phelps, well I've gone 0.1s faster without him in the pool.

"It was disappointing more than anything, to have a swim not count because of such a rule.

"But I would not take back that experience, it was part of the reason I knew I could swim that time today."

Trickett burst out in 25.40s, 0.33s under record pace, and flew home to improve her own official personal best by 0.52s.

The impressive front end speed bodes well for Trickett's 50m freestyle starting on Friday, where she'll aim to narrow the margin between herself and new world record holder, Dutchwoman Marleen Veldhuis.

"I would like to go a sub 24.5s, that would be ideal," said Trickett.

"I have been hanging around that time for a couple of years now.

"I feel like I am due for an improvement."

Sullivan motored down the pool in 21.41 seconds to shave 0.09s off the mark set by Frenchman Alain Bernard four days ago in Eindhoven, reclaiming the world record the West Australian set at the same pool last month.

He celebrated with a double-fist pump and a slap of the water, relieved to finally put his name back into the history books after two near misses and to prove to his doubters that his previous world record set here last month was no fluke.

"It's sort of sweet to get this back after missing (the 100m record) last night," said Sullivan, whose 100m victory last night secured his plane ticket to Beijing.

"There was less pressure than last night obviously after making it on the team and getting that (qualification) out of the way.

"I wanted that record really badly and I'm very, very pleased with myself."

Sullivan joins partner Stephanie Rice in having set two world marks this year, Rice etching her name into the books with 200m and 400m individual medley records at this meet.

The twin records takes the world record tally to six for this meet.

And Sullivan says he's not finished yet, he'll aim to give his new personal best a nudge on Friday night when he takes to the blocks for the final.

Breaststroker Leisel Jones almost joined in on the record-breaking spree, but faded over the final 50m to miss her own 200m record by 0.80s with a time of 2:21.34.

Gold Coaster Meagen Nay broke one of the oldest Australian records in the 200m backstroke semi-finals, with a time of 2:10.01 shaving 0.19s off Nicole Stevenson's mark set at the 1992 Barcelona Olympics.

South Australian Hayden Stoeckel broke the men's 200m backstroke Commonwealth record in winning his final, clocking 1:56.75 to better Matt Welsh's 2000 Olympic time of 1:57.59, with Victorian Ashley Delaney (1:57.53) second.

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