Ryan Murphy, right, consoled Isaac Cooper after winning gold ©Getty Images

American Ryan Murphy captured the men's 50 metres backstroke title but felt Isaac Cooper deserved the gold medal after a technical blunder cost the Australian victory at the World Swimming Championships (25m) here.

Cooper thought he had won his first individual world crown when he beat Murphy to the wall to register a world junior record of 22.49sec only for the result to be scrubbed off following a technical malfunction at the Melbourne Sports and Aquatic Centre.

Two swimmers had stopped when the buzzer sounded at the start of the race to raise alarm of the issue while the rest including Cooper and Murphy battled to the finish.

World Aquatics apologised for the mistake, claiming it was a "technical error by an official" and said a reswim had been "unanimously agreed".

Returning to the pool an hour later, a fired-up Cooper looked desperate to come out on top again as he led at the turn.

However, Cooper came up short as Murphy triumphed in 22.64 - 0.15 slower than the 18-year-old Australian recorded earlier.

"From my perspective, it was a little bit disappointing the way that it played out," said Murphy.

"I feel for Isaac.

"He's 18 years old, going for your first individual world title, that's huge and an incredible accomplishment.

"I talked to him real quick after the race, but I'm going to make sure to talk to him and let him know that in my mind, he won that race.

"It's definitely a mix of emotions."

Cooper had to settle for silver in 22.73, while Poland's Kacper Stokowski finished in 22.74 for bronze.

It was another thrilling night in the pool that saw three world records set and Australia’s golden girl Lani Pallister pick up her fourth title.

This evening’s session started in magnificent fashion with France turning on the style to break the mixed 4x50m freestyle relay world record.

American Michael Andrew had the edge over Frenchman Maxime Grousset in the first leg before Florent Manaudou produced a stunning swim to put France in front.

France kept getting faster with Beryl Gastaldello powering clear before Melani Henique finished the job to secure victory in 1:27.33 - half a second better than US team's previous world record.

Kate Douglass earned her third gold medal in Melbourne with victory in the women’s 200m breaststroke final ©World Aquatics
Kate Douglass earned her third gold medal in Melbourne with victory in the women’s 200m breaststroke final ©World Aquatics

The US missed out on a medal as Australia came back strongly to take silver in 1:28.03, while The Netherlands bagged bronze in 1:28.53.

Another record was broken in the women’s 200m breaststroke final as Kate Douglass set a championship best.

Lilly King was on world-record pace at the halfway point before being overhauled by Douglass who emerged victories, winning in 2:15.77.

It was Douglass' third gold in Melbourne having also won the women's 200m individual medley and mixed 4x50m medley relay.

The silver medal went to King in 2:17.13, while Tes Schouten of The Netherlands sealed bronze in 2:18.19.

Japan's Daiya Seto secured the eighth world short-course title of his career with an impressive performance in the men's 200m breaststroke final.

The Japanese star proved untouchable as he slammed down the accelerator in the closing 50m to triumph in 2:00.35 - a mere two hundredths of a second off Russian Kirill Prigoda's world record.

Nic Fink of the US clocked 2:01.60 for silver, while China’s Qin Haiyang notched 2:02.22 for bronze.

Canada's Maggie Mac Neil finished joint top with Torri Huske of the US in the women’s 50m butterfly two days ago but she was head and shoulders above the rest in the women’s 50m backstroke final.

Mac Neil powered to victory in 25.25, taking two thousandth of a second off her previous world record.

American Claire Curzan came second in 25.54, with Mollie O'Callaghan of Australia finishing third in 25.61.

There was Dutch delight in the women's 100m individual medley final as Marrit Steenbergen sealed top spot.

France's Gastaldello led at the halfway point only to be sucked into a three-way battle before being edged out by Steenbergen.

Steenbergen overcame Gastaldello and Sweden’s Louise Hansson to win in 57.53.

Gastaldello collected silver in 57.63 as Hansson earned bronze in 57.68.

Italy’s Thomas Ceccon was crowned men’s 100m individual medley champion following a blistering finish.

The Italian produced a storming swim from lane two to win in 50.97, seeing off the Canadian challengers of Javier Acevedo and Finlay Knox who clocked 51.05 and 51.10, respectively, for podium places.

One of the performances of day came from Pallister who dominated the field to win the women's 1500m freestyle title by a whopping 25 seconds.

Pallister was in sensational form as she eased to victory in 15:21.43 to capture her fourth gold of the tournament following victories in the women's 400m and 800m freestyle and 4x200m freestyle relay events.

Japan's Miyu Namba came home in 15.46.76, while Kensey McMahon of the US picked up bronze in 15:49.15.

The final race of the night saw another world record go courtesy of a stunning showing from the US team.

Kieran Smith, Carson Foster, Julian Trenton and Drew Kimber posted 6:44.12 - breaking the old 4x200m freestyle record held by Brazil by almost three seconds.

The silver medal went to Australia after notching 6:46.54, while a time of 6:49.63 saw Italy claim bronze.