New distance queen at Pan Pacs trials

Laine Clark
Kiah Melverton has dipped under 16 minutes in winning the 1500m freestyle at the Pan Pacs trials

A distance queen has emerged at Australia's Pan Pacs swimming trials in Adelaide - and it's not golden girl Ariarne Titmus.

Gold Coast Commonwealth Games bronze medallist Kiah Melverton has opened the five-day trials for August's Pan Pacs in Tokyo by claiming an upset win in new women's event, the 1500m freestyle.

The 21-year-old clocked 15 minutes, 59.92 seconds on Saturday night to become only the second Australian woman to crack the 16-minute barrier.

She held out 24-year-old Kareena Lee (16:00.14) with Maddy Gough (16:09.11) third.

Titmus, 17, still threatened to pick up at the trials where she left off at the Gold Coast Commonwealth Games.

Contesting only her second 1500m, Titmus led at the 800m mark before settling for fourth (16:09.87).

Titmus became the first woman since Tracey Wickham in 1982 to claim the 400m-800m freestyle Commonwealth Games double at the Gold Coast.

The teenager had also been the first Australian woman in 14 years to sweep the 200m-400m-800m freestyle treble at the 2018 national titles.

Remarkably, the top four finishers in Saturday night's 1500m final came under the Pan Pacs qualifying mark.

Australia's all-time women's 1500m top 10 got a rewrite as a result.

Melverton now sits second behind Jess Ashwood (15:52.17) while Lee is third with Gough and Titmus eighth and 10th respectively on the Aussie all-time list.

The 1500m has not been consistently raced in the past by women but is now a renewed focus after being added to the Tokyo 2020 pool program.

"We were hoping it (1500m) would be on the Olympic program and when it was added (for Tokyo), my coach Chris Nesbitt said to me 'this is your thing now'," Melverton said.

"This is a fairly new event for me so it's hard. You don't really know what you're doing - it's only my fourth or fifth 1500m."

Meanwhile, Rio Olympic 400m champion Mack Horton had to settle for silver behind Jack McLoughlin in the men's 800m freestyle final on Saturday night.

Horton clocked 7:56.05 behind Commonwealth 1500m champ McLoughlin (7:54.25).

Horton is one of 16 athletes at the Adelaide meet who have already met the Pan Pacs qualification standards.

Horton has switched his focus away from former pet event 1500m to 200m-400m-800m ahead of Tokyo 2020.

"I have shifted my training to 200m-400m and I'm just seeing how the change of stroke (for the 800m) was going," Horton said.

"I haven't really had the chance to race the 800m properly... (but) I think it's only going to get better and better over the years."