FUKUOKA, Japan -- China dominated the second day of the swimming world championships on Monday, winning back-to-back gold medals in the first 10 minutes of the session.
Zhang Yufei won the women's 100-meter butterfly and Qin Haiyang went wire-to-wire in the men's 100 breaststroke.
Zhang rallied over the final 15 meters, touching in 56.12 seconds. Margaret MacNeil of Canada finished second in 56.45, while Torri Huske of the United States clocked 56.61 for third two years after placing fourth in the event at the Tokyo Olympics.
The women's race was a repeat of the final two years ago at the Tokyo Games. The top four finishers in Tokyo were separated by only 14 hundredths of a second. That race went to MacNeil, followed by Zhang and Australian swimmer Emma McKeon. Huske was .01 behind McKeon and missed out on a medal.
Qin won his race only a few minutes before Zhang's triumph. After topping all other swimmers by more than one second in the semifinals, Qin was never challenged in the final.
There was a three-way tie for second place, with Nic Fink of the United States, Nicolo Martinenghi of Italy and Arno Kamming of the Netherlands all finishing in 58.72.
The men's race was partly defined by who did not compete. Adam Peaty, a two-time Olympic champion and world-record holder from Britain, is taking a break and is not swimming in Japan. He has said in interviews that he's taking time away for "mental health issues."
Peaty is one of the most dominant swimmers in his discipline and holds 19 of the top 20 times in the 100 breaststroke. His record is 56.88 seconds.
American swimmers Kate Douglass and Alex Walsh, college teammates at the University of Virginia, finished 1-2 in the women's 200-meter medley, with Yu Yiting of China in third. Douglass trailed until the final 50 meters when she overtook Walsh to win the gold medal in 2:07.17. Walsh picked up the silver in 2:07.97, while Yu took the bronze in 2:08.74.
The top-two finish by Douglass and Walsh marked the first time the American women had achieved the feat at the worlds.
Sixteen-year-old Summer McIntosh of Canada would have been a strong favorite in the event but she elected not to swim it because of a scheduling conflict. McIntosh finished a disappointing fourth the 400 free on Sunday - and lost her world record to Ariarne Titmus of Australia. McIntosh already holds the 400-medley mark, set earlier this year at 4:25.87.
Thomas Ceccon of Italy won the men's 50 butterfly, which is not an Olympic event, in 22.68. He finished ahead of Diogo Matos Ribeiro of Portugal in 22.80 and Maxime Grousset of France in 22.82.
Many of the men's butterfly events are missing top contenders, including Caeleb Dressel of the United States and Kristof Milak of Hungary. Dressel failed to make the team after taking a long break and Malik said he was not in shape - mentally or physically - to compete.