China's Qin Haiyang competes during the men's 200m breaststroke swimming heat at the 19th Asian Games in Hangzhou, China, Thursday, Sept. 28, 2023. Photo: AP
Qin shattered Australian Zac Stubblety-Cook's historical best at the July world championships in Fukuoka on his way to the gold medal with a blistering 2min 05.48sec.
The in-form star's 2:11.76 in the Hangzhou heats on day five of pool action was a long way off that, but he was cruising and had plenty left in the tank.
His teammate Dong Zhihao, who came fourth at the worlds, qualified third fastest with Hong Kong's Adam Mak splitting the Chinese pair.
Qin went on to complete an unprecedented sweep of the breaststroke races in Fukuoka to announce himself as the man to beat at the Paris Olympics next year.
He has already secured the 100m title at the Asian Games with the second-fastest time of 2023. He also won silver in the 200m medley and helped steer China close to two relay world records.
Qin is scheduled to swim the 50m breaststroke on Friday.
Hong Kong's Haughey, one of the world's top freestylers, clinched the Asiad 100 and 200m titles in blistering fashion.
The 50m is not her favoured event and she faces a blockbuster showdown in Thursday night's final against Zhang to complete the treble.
Like Haughey, Zhang is also chasing a third individual gold medal in Hangzhou after setting scorching times in winning the 100 and 200m butterfly. She also has two relay golds.
The Chinese superstar displayed her versatility in setting a new Games record of 24.50 to qualify fastest ahead of Haughey (24.94) and Singapore pair Quah Ting Wen (25.26) and Amanda Lim (25.26).
Japan's Rikako Ikee, the standout performer at the last Asian Games with six golds, failed to make the grade.
Ye Shiwen, a silver medallist in the 200m medley behind teammate Yu Yiting, touched in 2:27.09 to lead the pack into the women's 200m breaststroke final.
South Korea's Baek In-chul topped the timesheets in the men's 50m butterfly heats with China's Wang Changhao, who came second in the 100 fly, third fastest.
After narrowly missing world records in the men's 4x100m medley and 4x100m mixed medley races, China are overwhelming favourites to add more gold in the relays on Thursday evening.
They will be contesting the men's 4x100m freestyle and women's 4x200m freestyle, qualifying fastest in both, as they look to bolster the hosts' 19 swimming titles from 27 so far.
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