Mollie O’Callaghan has produced a sizzling last lap to triumph in the women’s 100m freestyle at Australia’s Olympic swimming trials.

O’Callaghan, last year’s world champion in the event, emerged victorious in a Friday night final in Brisbane raced without Olympic great Cate Campbell.

Campbell’s quest to swim at a fifth Olympics appears doomed after she missed the final by one hundredth of a second.

A cruelly timed illness in the lead-up to trials, and the narrowest margin in the sport, appear to have cost the 32-year-old her chance.

Campbell, a four-time Olympic gold medallist and former world-record holder and world champion in the 100m freestyle, was distraught after finishing ninth-fastest through Friday morning’s heats and missing a finals berth.

Campbell has one more event at the selection trials, the 50m freestyle on Saturday.

But it’s a long-shot she will secure a top-two finish and with it selection in the event at the Paris Olympics, given the presence of defending Olympic champ McKeon and O’Callaghan.

In the 100m final, the 20-year-old O’Callaghan made the turn in fifth place but blitzed the field in the final lap to win in 52.33 seconds from Shayna Jack (52.72).

Meg Harris (52.97) was third, followed by Bronte Campbell (53.10) while Emma McKeon, the reigning Olympic champion in the event, finished sixth in 53.33.

Meanwhile, Olympic champion Zac Stubblety-Cook hopes his two-year search for two missing seconds is completed in Paris.

Stubblety-Cook secured a defence of his Olympic crown with victory in the 200m breaststroke.

He touched in two minutes 07.40 seconds to win from Joshua Yong (2:08.08) – the winning time is almost two seconds outside of Stubblety-Cook’s personal best of 2:05.95 which was a world record set in May 2022.

That benchmark was broken at last year’s world championships by Qin Haiyan, one of 23 Chinese swimmers implicated in a doping furore before the 2021 Tokyo Olympics.

“I’m just still looking for my best race,” Stubblety-Cook said.

“It has been two years so I’d like to have my best race in Paris.”

Ella Ramsay won the women’s 200m breaststroke in 2:22.87 while second placegetter Jenna Strauch’s 2:24.04 is outside of the automatic Olympic qualification time set by Swimming Australia.

Men’s 1500m freestyle favourite Sam Short has withdrawn from Friday night’s final as he recovers from illness.

–AAP