The Hungarian is the Olympic champion in this race, and now the back-to-back world champion after his stunning triumph by more than three seconds.

Milák's time of 1min 50.34sec beat his previous world record time at the 2019 World Championships in Gwangju by 0.39.

He said afterwards that his achievement in Budapest "eclipses everything" he has achieved in his career to date.

France's Léon Marchand claimed silver in 1:53.38, while Tomoru Honda of Japan placed third in 1:53.61.

The fourth day's swimming finals began with high drama, as an incredible finish from the United States' Olympic champion Bobby Finke helped him to take men's 800m freestyle gold.

Finke was fourth with 50m remaining, but an astonishing final split of 25.93sec helped him to leapfrog Ukraine's Olympic bronze medallist Mykhailo Romanchuk, Germany's Florian Wellbrock and Italy's defending champion Gregorio Paltrinieri.

He also set an Americas record with his time of 7:39.36.

Wellbrock was second in 7:39.63, and Romanchuk third in 7:40.05.

This was the first time at a World Championships that the top three in the men's 800m freestyle final were separated by less than one second.

China won its first swimming medal in Budapest courtesy of Yang Junxuan in the women's 200m freestyle.

In a tight race, Yang staved off a late challenge from Australia's Mollie O'Callaghan to triumph in 1:54.92, with her closest challenger 0.30 further back.

Tang Muhan of China placed third in 1:56.25.

The other individual final of the day was won by the US' Nic Fink, who narrowly beat Italy's Nicolò Martinenghi to gold in the men's 50m breaststroke.

Fink's time of 26.45 was 0.03 quicker than the newly crowned 100m breaststroke world champion.

American Michael Andrew rounded off the podium in 26.72.

The mixed 4x100m medley relay final was the last race of the day, and won by the US team of Hunter Armstrong, FInk, Torri Huske and Claire Curzan.

They clocked 3:38.79, beating the 3:41.34 posted by 2019 world champions Australia.

The Netherlands rounded off the top three in 3:41.54, meaning Olympic champions Britain - missing stars Kathleen Dawson and Adam Peaty through injury - missed out on the podium by 0.16 in fourth.

Earlier in the day, China won women's team technical routine gold in artistic swimming.

They notched a score of 94.7202, beating Japan's 92.2261.

Third-placed Italy received 91.0191 for their routine.

Finals are set to continue tomorrow on the fifth day at the FINA World Championships, with medals to be decided in swimming in the women's 200m butterfly, men's 100m freestyle, women's 50m backstroke, men's 200m individual medley and women's 4x200m freestyle relay.

The solo free final in artistic swimming is also scheduled.