Caeleb Dressel already had two golds draped around his neck in Gwangju and on Thursday the American got another one in the blue riband event -- the 100 freestyle.
Another day, another controversy at the world swimming championships, with American Lilly King's disqualification from the women's 200 metres breaststroke on Thursday proving the latest headache for governing body FINA.
The championships have been marred by podium protests over the presence of China's Sun Yang, who served a doping sanction in 2014 and was cleared to compete at the worlds despite another doping case pending at the Court of Arbitration for Sport.
That case involves an aborted out-of-competition test last year in which Sun was alleged to have refused to cooperate with testers and one of his blood samples ended up being destroyed with a hammer.
A report of the FINA Doping Panel hearing that was leaked to an Australian newspaper backed Sun's claim that the testers did not have proper accreditation and said he was within his rights to refuse the test.
After Sun's victory in the 400 freestyle on Sunday, silver medallist Mack Horton refused to share the podium with him, while British bronze medallist Duncan Scott would not shake his hand or pose for a group photo with Sun after Tuesday's 200.
The protests have prompted FINA into adding a clause to their code of conduct calling on swimmers to avoid "offensive or improper behaviour" during a competition.
However, Olympic and world breaststroke champion Adam Peaty said swimmers should have the right to express their opinion.
“There shouldn’t be any warning shots fired at them for having freedom of speech,” the Briton said at a news conference.
“When you go around smashing vials, it’s not right. You shouldn’t be in the sport at all.”
Sun's coach Denis Cotterell, who has worked on and off with the Chinese Olympic champion for 11 years, said the implication that he would coach a drug cheat was an "insult".
"If you think for a second I would be doing that with someone that is a cheat, then people don’t know me," said Australian Cotterell.
"What is the definition of a drug cheat? Someone who has failed a test?....
"I have been on teams where people have failed a drug test, accidentally and through no fault of their own. I would never call them cheats. It seems to be very hypocritical."
On Thursday FINA came under fire for the controversial decision to disqualify Olympic 100 breaststroke champion King for a "non-simultaneous touch" at the first turn of her heat.
The result of USA Swimming's appeal was only made known minutes before the start of the evening session, prompting fresh criticism.
In King's absence her great rival Yuliya Efimova, who served a 16-month doping ban in 2013, posted the quickest time of the semi-finals (2:21.20) while in the men's semi Australian Matthew Wilson equalled Ippei Watanabe's world record of 2:06.67.
A world record did fall on Thursday, with the Australian women's 4x200 freestyle relay team setting a new mark of 7:41.50, shaving 0.58 seconds off the record set by China in Rome 10 years ago.
Caeleb Dressel already had two golds draped around his neck in Gwangju and on Thursday the American got another one in the blue riband event -- the 100 freestyle.
Dressel, who in 2017 matched Michael Phelps' record of seven world titles at a single championship, blazed away from the blocks and just held on from Olympic champion Kyle Chalmers, winning gold in 46.96 -- the second-fast time ever.
"I know I was just off the world record but really the goal was just to swim the best race that I could and if that was the time I got tonight I was happy with that," said Dressel, who also won gold in 2017.
The women's 200 butterfly final also saw a thrilling finish, with Hungary's Boglarka Kapas running down American Hali Flickinger on the home stretch.
The last of the eight swimmers to turn at the halfway mark, European champion Kapas turned on the jets with 50 to go and touched first in 2:06.78 -- 0.17 seconds ahead of Flickinger.
There was also gold for 2020 Olympics hosts Japan with Daiya Seto winning the men's 200 individual medley while American Olivia Smoglia touched the wall just before Brazil's Etiene Medeiros in the 50 backstroke final.
Australia women set world record
Australia set a world record of 7:41.50 en route to winning the gold medal in the women's 4x200 freestyle relay at the world championships on Thursday.
The quartet of Ariarne Titmus, Madison Wilson, Brianna Throssell and Emma McKeon knocked 0.58 seconds off the previous mark set by China at the Rome worlds in 2009.
The United States (7:41.87) took silver and Canada (7:44.35) the bronze.
"Just touching the wall and seeing the three others celebrate, it made me so excited," said McKeon, who swam the anchor leg. "I wasn't thinking about a world record, that was the key."
Titmus, who beat American great Katie Ledecky to gold in the 400 freestyle on Sunday, said she knew she would have to pull her weight if they were to have a shot at the record.
"I really wanted to do my job for the girls, if we really wanted to have a crack at the world record I would have to play my part," she added.
The Americans' time was also under the previous world record and while Ledecky, who pulled out of the 200 and 1,500 freestyle due to illness this week, was disappointed not to win gold she took some solace from the time.
“It's just cool whenever you break the world record," she said. “We know we swam one of the fastest times ever so it was pretty cool."
The 22-year-old, who has so far failed to add to her haul of 14 world titles in Gwangju, said she had been feeling the effects of dehydration, loss of appetite and light headedness but that she was "95% sure" she would swim in the 800.
"It’s just one of those things where you have to put your health first and put my trust in our great medical staff, who did a tremendous job of getting me back on a path to try and resurrect the second half of this meet."
