Sore Sun's countdown conundrum

As far as the new breed is concerned, there were some encouraging signs in Qingdao.

Xu Jiayu, 21, broke the Asian record in the men's 100m backstroke with a time of 51.86 seconds, just 0.01 sec shy of the world record, and smashed his own national marks in the 50m and 200m backstroke.

"My upper-body strength has been enhanced and I'm happy that I improved my personal bests," said Xu, who grabbed silver in the 100m backstroke in Rio and won four golds at the championships.

Yan Zibei from Hubei province, also 21, set new national marks in the men's 50 and 100m breaststroke.

"I don't think too much about the Olympics, and I will try my best to improve step by step. This year, my main objective is the National Games (in Tianjin in August)," Yan said.

Eighteen-year-old Li Zhuhao, Sun's provincial teammate from Zhejiang, broke the national record in the men's 50m butterfly and pocketed three golds.

The Chinese Navy's Qin Haiyang, 17, broke two world junior records and the national record in the men's 200m breaststroke, and his time in the 200m individual medley ranks third in the world this year.

"I'm surprised I swam so fast; perhaps it's my winter training that made it happen," Qin said.

However, Qin's coach, Ye Jin, was far from surprised. "His technique has improved a lot, and I think he has a bright future," she said. On the women's side, Fu Yuanhui, 21, improved her personal best in the 100m backstroke to set a Chinese record of 58.72 sec, 0.04 sec faster than her Olympic bronze medal-winning time in Rio last year.

Most promising, perhaps, were the results of 15-year-old Li Bingjie, whose times in the 400m and 800m freestyle are this year only inferior to double Olympic champion Katie Ledecky of the US.

"Li Bingjie is only 15, and other female swimmers are very young as well," said Liu Haitao, one of China's coaches. "Their performances are satisfying, but we need to give them more time.

"I hope the youngsters can train as hard as they can and get the best possible marks at the Tokyo Olympics."