After capturing the women’s 400 metres freestyle crown yesterday, Pallister swept to the women’s 800m freestyle title before leading Australia home in a superb showing in the women’s 4x200m freestyle relay final at the Melbourne Sports and Aquatic Centre.

Pallister has overcome a series of health issues, including undergoing a heart procedure last year, to be crowned a triple world champion in Melbourne.

The 20-year-old produced a brilliant final leg as Australia finished in 7min 30.87sec, shaving almost two seconds off the previous world record held by The Netherlands.

Canada got off to a blistering start as Rebecca Smith put her team under world-record pace.

With the crowd behind them, the Australian team then came to the fore with Mollie O’Callaghan overtaking Canada's Katerine Savard.

Leah Neale produced a terrific third leg to put Australia in complete command before Pallister brought it home.

Canada had to settle for silver in 7:34.47, while the United States collected bronze in 7:34.70.

Pallister was diagnosed with supraventricular tachycardia - a condition that can cause an irregular heartbeat - before undergoing a procedure to fix the issue.

She has also struggled with an eating disorder and contracted COVID-19 in a torrid 18-month period but has been in fine form in Melbourne, winning the women’s 800m freestyle gold in dominant fashion.

Twenty four hours earlier, Erika Fairweather was her biggest challenger but the New Zealander was unable to mount a comeback against Pallister who got stronger as the race wore on, storming clear to claim victory in 8:04.07.

Fairweather came second in 8:10.41, with Japan’s Miyu Namba coming third in 8:12.98.

Ryan Murphy and Torri Huske bagged two golds each on a memorable night for the US.

The pair helped the US break the mixed 4x50m medley relay world record, with Murphy getting them off to a flying start before Huske completed the job.

Murphy, a four-time Olympic gold medallist, then powered to victory in the men’s 100m backstroke final to take his short-course world title tally to six.

Huske also delivered individual gold, sharing the women’s 50m butterfly crown with Canada’s Margaret MacNeil.

After two world records were broken in the final two races of last night’s action, another was smashed at the start of this evening’s medal session thanks to a stunning performance from the US team.

Murphy sent the US on their way with a strong opening leg, notching a split of 22.37 before Nic Fink kept up the pace.

Italy were pushing the American team hard with Lorenzo Moro and Nicolo Martinenghi producing good performances.

The US found an extra gear with Kate Douglass, a winner of the women’s 200m individual medley, forging clear before Huske led them home, securing victory in 1:35.15 as the US broke the world record.

The silver medal went to Italy who finished in 1:36.01 to notch a new European record.

The Netherlands looked like they had claimed bronze in 1:36.40 only to be disqualified, bumping Canada up to third with a time of 1:36.93.

Murphy claimed his second gold of the day when he stormed to the men's 100m backstroke title.

The American came storming out of the blocks and did not look back, clinching gold in 48.50 to set a Championship record.

Italy’s Mora came back strongly in the final 50m but was unable to overhaul Murphy as he came second in 49.04.

Australia’s Isaac Alan Cooper pulled off a fine showing from lane one to earn bronze in 49.52.

A thrilling finish saw Australia’s Kaylee McKeown snatch the women’s 100m backstroke crown.

Sweden’s Louise Hansson led for much of what was a closely-fought race as she aimed to retain the title only to be overtaken in the final 25m.

McKeown clawed her way back from fourth position at the halfway point to clinch victory in a dramatic finish, edging compatriot O’Callaghan.

There was just 0.13 separating the two swimmers, with McKeown touching first in 55.49 as O’Callaghan sealed silver in 55.62.

Claire Curzan of the US and Canada’s Ingrid Wilm shared the bronze in 55.74 as Hansson missed out on a medal in 55.89.

The women’s 50m butterfly final proved to be even closer with Huske and MacNeil touching the wall at exactly the same time, finishing in 24.64.

MacNeil was down in last place at the first turn before surging back to match Huske at the finish.

China’s Yuri Zhang was just 0.06 behind in third, edging out French duo Beryl Gastadello and Melanie Henique.

Ageless Nicholas Santos boosted his collection of short-course world crowns to six with more men’s 50m butterfly success.

The 42-year-old retained the title in a Championship record time of 21.78, winning it for the third time.

Switzerland’s Noe Ponti sealed silver in 21.96, while Szebasztián Szabó of Hungary picked up bronze in 21.98.