Butterfly specialist China's Zhang Yufei won her fifth gold medal of the Asian Games on Thursday when she edged Hong Kong's Siobhan Haughey to win the 50m freestyle, while South Korea wrought vengeance on hosts China in front of a frenzied eSports crowd.

Zhang powered to the finish in a new Games record 24.26sec with 100 and 200m freestyle champion Haughey second in 24.34 and China's Cheng Yujie third in 24.60.

Similarly, the world record holder Qin Haiyang powered to the Asian Games 200m breaststroke title adding it to his 100m crown.

Qin hit the wall in a new Games record 2:07.03, well outside his 2:05.48 world mark set in July but enough to easily beat teammate Dong Zhihao (2:08.67) and Japan's Ippei Watanabe (2:09.91).

Hosts China have hoovered up the golds in Hangzhou in everything from beach volleyball and gymnastics to table tennis and wushu, sitting way clear at the top of the medals table.

They have extended that dominance to the pool, one of the most eagerly anticipated events of the Games and boasting Olympic and world champions.

There is added interest this time because the Paris Olympics are less than 10 months away.

Overall China is leading the Games with a whooping 88 gold medals while South Korea is second with 22 and Japan is sitting in the third place with 18 gold medals.

China have plundered 19 of the 27 golds so far in swimming, with Zhang and Qin Haiyang both firing warning shots to their Olympic rivals.

The 25-year-old Zhang is 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 to add to her collection.

She qualified fastest for the 50m freestyle final later Thursday and will go head-to-head with Hong Kong's Haughey, who has already won the 100 and 200m free.

Gold medals were up for grabs on Thursday in 12 sports, among them artistic gymnastics, track cycling and shooting.

In eSports — which is making its debut at the Games as a medal event — South Korea's Kim Gwan-woo will contest the final of Street Fighter V: Champion Edition.

South Korean athletes at the Games, including eSports players, can controversially earn an exemption from military service if they come home with gold.

Also in eSports, in a rerun of the final five years ago — when it was only a demonstration sport — South Korea defeated China in the semi-finals of League of Legends.

It was revenge for South Korea and their legendary player Lee "Faker" Sang-hyeok, having lost to China in 2018.

"From the beginning my goal as a coach was to win the title with the team," said South Korea coach Kim Jeong-gyun.

"We have trained more than anyone this month and I believe we can win."

The eSports events have proven to be wildly popular with fans, with tickets in strong demand and the overwhelmingly young spectators giving hearty support from the stands.

Fans unable to get into the futuristic-looking 4,500-capacity Hangzhou Esports Center thronged outside in the hope of catching a glimpse of one of their heroes, especially Faker.

On the first day of golf, Japanese amateur Saki Baba shot a seven-under 65 to take a surprise lead in the women's event.

But it couldn't spoil Yin Ruoning's 21st birthday.

The world number two Yin was two shots back in a five-way tie for second after a flawless 67 in front of her home crowd.

"It's not bad to have a bogey-free round for my 21st," smiled Yin, known affectionately as "Ronnie" on the LPGA Tour, after she flew out of the blocks with five birdies in her first eight holes