Ariarne Titmus and teammate Mollie O’Callaghan have both shattered the 200m freestyle world record in a thrilling head-to-head at the Australian Olympic Swimming trials.

But the new world record title goes to Titmus who pipped O’Callaghan with a time of 1:52.23 to O’Callaghan’s 1:52.48 on Wednesday night.

In an electric duel ahead of the Paris Olympics, both swimmers bettered O’Callaghan’s record (1.52.85) which was set only last year at the world championships.

The freestyle golden girls rewrote the history books in an epic swim battle that could be one of the “greatest” races ever.

Such was the dominance of Titmus and O’Callaghan they finished more than three seconds ahead of the rest of the field.

Titmus now holds the 200m and 400m freestyle world records and is reigning Olympic champion in both events.

“Honestly, the world record is a bonus,” she said poolside at the Brisbane Aquatic Centre on Wednesday.

“I am happy to finally put together a swim that I know I’m capable of and it’s exciting to do it in my home town.”

Nine commentator Mat Thompson declared the double world record battle was “one of the greatest races of all time”.

“She might be the best we’ve ever had,” he said. “She’s got a chance to come back from Paris as Australia’s greatest ever swimmer.”

Giaan Rooney said she was “speechless”.

“0.62 off the world record that was only broken last year.”

Titmus didn’t tap into O’Callaghan’s feat at last year’s world titles in Japan for motivation, despite both swimmers being coached by Dean Boxall.

“We really don’t see what each other is doing in training, we are very separate — she trains for the sprint events, I train for middle distance,” Titmus said.

“Looking at a world record, I don’t look at who has it. I look at the time.”

O’Callaghan admitted to severe pre-race anxiety stemming from entering the final as the record holder.

“I couldn’t really sleep last night,” she said.

But the 20-year-old instantly put a positive spin on losing the record.

“It really takes the pressure off me, because coming into this (meet) I was not in a good place,” she said.

Shayna Jack tied for fifth, securing a debut Olympic appearance after serving a two-year doping ban from 2019.

The top six in the final —Titmus, O’Callaghan, Lani Pallister, Brianna Throssell, Jack and Jamie Perkins — will comprise Australia’s 4x200m freestyle relay squad in Paris.

Cameron McEvoy wins the Men’s 50m freestyle final. Photo: Getty

Cameron McEvoy became the first Australian male swimmer to qualify for four Olympics after winning the 50m freestyle in 21.35 seconds.

“It’s special because you could almost fill a book with legendary Aussie male names in the sport,” the 30-year-old said.

“To have the privilege of having that title, having that type of longevity … it shines a lot on the persistence and perseverance that I have had.”

McEvoy took a break from the sport before returning with a revolutionary training approach which includes rock climbing and calisthenics rather than huge amounts of swimming.

“My goal was to just come back, give this new training approach a go and see what happens,” he said.

“What I have done so far has just obliterated any expectations I had.”

Bowen Gough won the men’s 200m butterfly in 1:56.18 from Harrison Turner (1:57.07).

Both were outside the automatic qualifying time for the Games set by Swimming Australia, leaving their Olympic hopes resting on selectors’ discretion.

-with AAP