Ariarne Titmus smashed the 200 metres freestyle world record at Australian Olympic trials in Brisbane on Wednesday, upsetting the previous holder Mollie O’Callaghan in an exhilarating final.

Olympic champion Titmus clocked a time of one minute and 52.23 seconds to shave more than half a second off O’Callaghan’s previous mark (1:52.85) from last year’s World Championships in Fukuoka.

“Looking at the results, that’s unbelievable,” Titmus said pool-side.

“I’m just happy to finally produce a swim in the 200 that I feel like my training reflects.

“I think the field that we have is why we’re swimming so fast, we push each other every day.”

The final was a rematch of the Fukuoka event, when O’Callaghan edged Titmus in a thriller for the title.