Qin Haiyang of China set the world record in the men's 200-meter breaststroke Friday, winning the gold medal in a time of 2:05.48 at the swimming world championships.
Qin bettered the previous record of 2:05.95 set by Australian Zac Stubblety-Cook at the 2022 Australian championships in Adelaide. Qin finished 0.92 seconds ahead of silver medalist Stubblety-Cook. Matt Fallon of the United States took bronze.
This was Qin's third gold at the worlds. He also won the 50 and 100 breaststroke, becoming the first man to sweep all three breaststroke events at the same worlds.
Qin wasn't as elated about his world record as expected, saying his true "dream" is to break the 100 breaststroke mark.
Australia's Mollie O'Callaghan completed a sprint double by winning the women's 100 freestyle to complete a sprint double. She trailed at the turn but surged in the final 25 meters to capture gold in a time of 52.16 seconds and defend her title.
Australia had dominated the event with three titles in the previous five championships thanks to victories by O'Callaghan in Budapest, Hungary, in 2022; Bronte Campbell in Kazan, Russia, in 2015; and Cate Campbell in Barcelona, Spain, in 2013.
The 19-year-old O'Callaghan ensured that run continued by finishing strongly after a sluggish start to edge out Siobhan Haughey of Hong Kong, who grabbed silver in 52.49 seconds.
O'Callaghan became the first woman to win the 100 and 200 titles at the same worlds.
"I came into this week wanting to have fun and enjoy it and learn. To have achieved so much is an incredible feeling," said O'Callaghan, who overcame a knee problem to set a world record in the 200 on Wednesday. "Having fun is the most important part. Going into previous meets, I was just so nervous all the time and worrying, and this is the first time that I've actually felt quite calm and just enjoying every little bit."
Friday's triumph was O'Callaghan's fourth gold of the meet, following wins as part of Australia's 4x100 freestyle and 4x200 freestyle relay teams -- also in record times.
Marrit Steenbergen of the Netherlands took bronze after finishing 0.55 seconds behind O'Callaghan. Australian Olympic champion Emma McKeon was fifth in 52.83.
In the women's 200 breaststroke, South Africa's Tatjana Schoenmaker cruised to her country's first-ever world championship gold by a woman. The Olympic champion touched the wall in 2:20.80 with Kate Douglass of the United States second and Tes Schouten of the Netherlands rounding out the podium. American Lilly King, the 2022 champion, was fourth.
"We're racing some of the world's best," said Schoenmaker, who won silver in the 100 breaststroke earlier this week. "And coming back from the Olympics, it was a tough two years, so I'm just grateful I was able to have the opportunity to race some of these girls."
Hungary's Hubert Kos dethroned American Ryan Murphy to win the men's 200 backstroke in 1:54.14. Murphy had led through the first half of the contest but ran out of steam to finish 0.69 seconds behind for silver. Swiss Roman Mityukov was more than a second slower in taking bronze.
Kos, the son of an American father and Hungarian mother, began training about seven months ago at Arizona State under Michael Phelps' long-time coach Bob Bowman, who is also the coach of the American team at the worlds.
"A year ago, I was only swimming the 200 IM in the world championships," Kos said. "I never thought I'd be swimming backstroke, and here I am a world champion.
"I think it's just the Bob Bowman effect," he added. "That's as simple as it is. We have a really good training group, and Bob knows a thing or two about swimming."
Bowman is also training Leon Marchand at Arizona State. The French swimmer has won three gold medals at worlds and figures to be the face of next year's Paris Olympics.
Kos said he went to Arizona State to work on his IM, but Bowman make the switch. He called Bowman's touch partly "magic."
"The other part is he's just been there for so long and done everything with Michael, and now he's doing the same stuff with Leon," Kos said.
Britain won gold to end the day as its men's 4x200 freestyle relay team of Duncan Scott, Matthew Richards, James Guy and Tom Dean finished in 6:59.08 to beat the U.S. (7:00.02) and Australia (7:02.13) to the title. The top three relay finishers qualified for the Paris Olympics.
Through six of eight days, Australia leads with 10 gold medals, followed by China with five and the United States and France with three. The Americans lead the overall medals table with 25, ahead of Australia with 16 and China with 10.
Reuters and The Associated Press contributed to this report.