Two of Murphy’s titles came tonight as he triumphed in the men's 200 metres backstroke final before helping the US share men's 100m individual medley relay gold with Australia after they both broke the world record.

It was a pulsating end to the tournament as the US and Australia dashed Italy’s hopes with an incredible finish at the Melbourne Sports and Aquatic Centre.

Alessandro Miressi was in front going into the final 25m only for Australia's Kyle Chalmers and Kieran Smith of the US to pull off splits of 44.63sec and 45.95, respectively, to hit the wall at the same time.

Murphy, Nic Fink, Julian Trenton and Smith of the US and the Australian team of Isaac Cooper, Josh Yong, Matthew Temple and Chalmers both clocked 3min 18.98sec, taking 0.18 off the world record previously held by the Russian Olympic Committee (ROC).

Italy also beat the ROC's time, finishing 0.08 behind the US and Australia to take bronze.

The dead heat came just minutes after Murphy took to the podium to collect his men's 200m backstroke gold.

There was no stopping Murphy who came out on top in 1:47.41, defeating compatriot Shaine Casas by 0.60.

Italy’s Lorenzo Mora came home in 1:48.45 for bronze.

Murphy's three other golds came in the men's 50m and 100m backstroke and 4x50m medley relay.

Douglass also finished with five golds with her last coming in the women’s 4x100m medley relay where the US broke the world record.

The 21-year-old anchored the American team featuring Claire Curzan, Lilly King and Torri Huske home as they won in 3:44.35, shaving 0.17 off their own record.

Australia clinched silver in 3:44.96 and Canada came third in 3:46.22.

Douglass also claimed golds in the women's 200m breaststroke, women's 200m individual medley, 4x50m freestyle relay and 4x100m medley relay.

The US topped the medal standings with 17 gold, including three on the final night.

The last session was stacked with 10 finals and this evening's action got off to a stunning start courtesy of Canada's Maggie Mac Neil's record-breaking victory in the women’s 100m butterfly final.

Huske burst out of the blocks and led at the second turn with Mac Neil and Sweden's Louise Hansson breathing down her neck.

Defending champion Mac Neil then overhauled Huske before powering to the finish, winning in 54.05 to break the world record by almost half a second.

Huske boosted her medal tally with silver in 54.75 as Hansson clocked 54.87 for bronze.

After a four-year world title drought, two came in quick succession for South Africa's Chad le Clos as he chases American Ryan Lochte's all-time record.

Le Clos had the bit between his teeth as he powered to men's 100m butterfly gold in 48.59.

His victory came just two days after winning the men's 200m butterfly crown, moving his overall gold-medal haul to 12 - just two behind Lochte's record of 14 individual world short course titles.

Canada's Ilya Kharun set a world junior record of 49.03 to take silver as Germany’s Marius Kusch bagged bronze in 49.12.

Lithuania's Rūta Meilutytė delivered gold with another emphatic performance in the women’s 50m breaststroke.

Meilutytė was the heavy favourite to come out on top after breaking the world record in yesterday's semi-finals and lived up to that billing.

The Lithuanian secured the title for the second successive year in 28.50 as South Africa's Lara van Niekerk earned silver in 29.09 and King sealed bronze in 29.11.

Fink saw off the Italian challenge of Nicolo Martinenghi and Simone Cerasuolo to clinch men's 50m breaststroke gold.

The American set a championship record in 25.38 - beating Martinenghi by just 0.04, while Cerasuolo was 0.30 further back in third.

It was Fink’s third gold in Melbourne after his wins in the men's 100m breaststroke and 4x50m medley relay before being part of the men's 4x100m medley relay success in the last race of the evening.

Australia's first title of the night came from Kaylee McKeown who made history in the women's 200m breaststroke.

McKeown became the first woman to hold the Olympic, Commonwealth Games and world short and long course titles simultaneously in the event.

The 21-year-old came under pressure from Curzan but responded superbly, sealing the top spot in 1:59.26 to complete a hat-trick of golds in Melbourne.

Curzan came second in 2:00.53, while Canada's Kylie Masse bagged bronze in 2:01.26.

Siobhán Haughey of Hong Kong retained the women's 200m freestyle crown after touching the wall first in 1:51.65.

The other podium places went to Canada's Rebecca Smith and Marrit Steenbergen of The Netherlands who registered times of 1:52.24 and 1:52.28, respectively.

Arguably the best individual performance of the night came from South Korea's Hwang Sun-woo who set a championship record to win the men’s 200m freestyle gold from lane one.

Britain’s Tom Dean was the favourite after posting the quickest time in qualifying but it was Hwang who starred from the outside lane.

It was superb swim from the South Korean who clocked 1:39.72 for victory, beating Romania's David Popovici who clinched silver in 1:40.79, while Dean notched 1:40.86 for bronze.