World champion Qin Haiyang surged to the world's second fastest time this year and the Asian Games 100m breaststroke title Monday while star freestyler Siobhan Haughey clinched Hong Kong's first-ever swimming gold medal.
China won four of the seven titles on offer in the Hangzhou pool, but Haughey and South Korea's Ji Yu-chan denied them a clean sweep, taking out the women's 200m freestyle and men's 50m freestyle crowns respectively.
South Korea also upset China in the men's 4x200m freestyle, but needed a new Asian record to do so.
Chinese superstar Qin was the overwhelming favourite after a stunning swim to win the world championship this year in Fukuoka in the absence of British great Adam Peaty.
He went on to complete an unprecedented sweep of the breaststroke races, an achievement he is aiming to match at his home Asiad as he builds towards next year's Paris Olympics.
He first cracked the Asian Games record in the heats and bettered it again in the final to touch in 57.76sec -- the second quickest of 2023 after his world championship-winning exploits.
Qin finished a gaping 1.33sec ahead of teammate Yan Zibei with South Korea's Choi Dong-yeol bagging bronze.
"I'm quite pleased with the result today. My form is quite similar to what it was at the world championships, and I'm trying out some new race strategies," he said.
"I'm more aggressive in the first half of my swims, going faster."
It ensured yet another gold medal for the dominant hosts, whose four on day two added to the seven-from-seven they won on Sunday.
Qin had already claimed a silver after finishing second to storming Olympic champion Wang Shun in the 200m medley on the opening night of action.
- 'Win everything' -
Haughey, one of the world's top freestylers who won silver at the Tokyo Olympics behind Australia's Ariarne Titmus, was also in scintillating form.
She pulled clear over the opening 50m and never looked back to touch in 1:54.12, leaving China's Li Bingjie and Liu Yaxin in her wake.
It was her first Asian Games gold after missing the previous edition in 2018 with an injury.
"It's very special," she said of winning Hong Kong's maiden gold in the pool.
"I guess I was hoping for a little faster time, but it's not too far off my best time, so I'm still happy with it."
Meanwhile, China's Yu Yiting backed up her 200m medley world championship bronze with Asian Games gold.
The 18-year-old swam a new Games record time of 2:07.75 to hold off charging teammate Ye Shiwen and South Korea's Kim Seo-yeong.
China's Xu Jiayu successfully defended his 50m backstroke title, adding to the 100m gold medal he had already claimed in Hangzhou.
The 28-year-old world bronze medallist touched in 24.38 ahead of teammate Wang Gukailai.
"There's no one event that I put greater emphasis on. I want to do well in all of them, and my target is to win in everything I take part in," said Xu.
China's Wang Xueer powered to the women's 50m backstroke gold in 27.35 to edge out compatriot Wang Letian and Miki Takahashi of Japan.
South Korea's Ji smashed his own Asian Games record in winning the men's 50m freestyle gold, surging home in 21.72 to edge Hong Kong's Ian Ho and Chinese star Pan Zhanle, who had swum a monster 46.97 on Sunday to take 100m gold.
South Korea spoiled the hosts' party in the final race of the night when they won the 4x200m freestyle relay in a new Asian record time of 7:01.73.
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