From the eight finals contested, they won five at the Hangzhou Olympic and International Expo Centre, the first in a world record time.

Amreica's women’s team won their 4x50 metres medley relay final in a record time of 1min, 42.38sec, surpassing the previous best – also held by the US - by almost a second.

The time saw the team of Olivia Smoliga, Katie Meili, Kelsi Dahlia and Mallory Cornerford finish two seconds ahead of China, who took the silver medal, and The Netherlands, who claimed bronze.

Those two teams touched the wall in 1:44.31 and 1:44.57 respectively.

A second world record of the day came in the night’s other relay and once again from the US, in the mixed 4x50m freestyle final.

The quartet of Caeleb Dressel, Ryan Held, Commerford and Dahlia touched the wall in 1:27.89, comfortably faster than the previous record of 1:28.39 set by The Netherlands last year.

The former world record holders had to settle for the silver medal this time around, while Russia claimed the bronze.

America won the men’s 100m backstroke, where Ryan Murphy held off China's world record holder Xu Jiayu to win in 49.23sec.

As the short races often are, it was incredibly close, with Jiayu touching the wall three-hundredths of a second behind. 

"It was super close," Murphy said.

"It wasn't the cleanest race from me, but it's good to come out on top.

"This is only my second ever time racing over the short course."

The bronze medal in that race was claimed by Russia’s Kilment Kolesnikov who finished in 49.40.

In the men’s 200m freestyle, America's Blake Pieroni triumphed from lane eight.

The US star set off very fast and was clearly tiring by the end but was far enough ahead to claim the gold medal in 1:41.49.

The silver medal went to Lithuania’s Danas Rapsys and the bronze to Australia’s Alexander Graham.

America's fifth gold medal came from Smoliga, who won her second of the day in the women’s 100m backstroke final having earlier swam in the 4x50m medley relay. 

She managed to surpass the favourite and world record holder Katinka Hosszú, of Hungary, to win in 56.19, seven-hundredths of a second ahead of her rival.

The bronze ended up being shared by Georgia Davies from Great Britain and Australia’s Mina Atherton, who both finished in the identical time of 56.74.

Another big story from today came in the men’s 100m breaststroke final where South Africa’s Cameron van der Burgh won gold in 56.01 but then immediately announced his retirement. 

The 30-year-old clearly wanted to bow out on a high, having taken his gold in a Championship record time ahead of Belorussian Ilya Shymanovich and Japan’s Yasuhiro Koseki.

In announcing the news he thanked "every person" that has been a part of his career.

“Swimming has given me so much and has springboarded me to the next part of my future,” van der Burgh, Olympic gold medallist in the 100m breaststroke at London 2012 and winner of the silver at Rio 2016, said.

"Twenty eighteen has definitely been the best year of my life."

Earlier in the year the former Olympic champion got married and won the 50m breastroke at the Commonwealth Games in the Gold Coast.