QINGDAO, China, April 16 -- Xu Jiayu couldn't wait for his show in the final as he broke the national record of the men's 50m backstroke in the semifinals at the Chinese Swimming Championships here on Sunday.

Xu, 21, led the semifinals in 24.42 seconds, slicing 0.16 seconds off the previous national record.

The backstroke specialist has already won two individual gold medals both in record-breaking results.

As the Olympic silver medalist, he broke the Asian record of the men's 100m backstroke on Wednesday and his result of 51.86 seconds is only 0.01 second shy of the world record. Then he bettered his own national record of the 200m backstroke by 0.76 seconds to one minute and 54.03 seconds.

The 18-year-old Li Zhuhao made a sweep in the butterfly events after winning the men's 100m race in 51.63 seconds.

Earlier this week, he won the 50m event by breaking the national record in 23.36 on Tuesday and took the first place in the 200m race in one minute and 55.09 seconds.

More surprisingly, the 33-year-old Zhou Jiawei was still competitive nationwide as he ranked third in 52.60 seconds.

"I just want to enjoy the race and be a model for our team's younger swimmers," said Zhou representing team Guangdong, who retired in 2013 after winning the 100m butterfly event four times in a row at the National Games.

"I returned to training for more than one year and I'm also a coach now," said Zhou. "I have to say that it's not easy for me to be an athlete again. I'm not young and I have my family, my son to take care of. "

"But as long as my team needs me, I will keep swimming," said Zhou, who is expected to take part in his fifth National Games four months later.

Li Bingjie dominated the women's 800m freestyle final in eight minutes and 20.89 seconds.

The 15-year-old Li clinched the title of the 400m freestyle on Tuesday and finished second in the 200m freestyle.

In other actions, veteran Lu Ying took the gold of the women's 50m butterfly in 25.85 seconds. Yu Hexin led the men's 50m freestyle final in 22.46 seconds. Chen Jie won the women's 200m backstroke in two minutes and 09.29 seconds.

In the morning session, Sun Yang finished second in the 1,500m freestyle heats while Qiu Ziao, 18, reached the final as the top qualifier in 15 minutes and 18.14 seconds, 0.53 faster than Sun.

The 25-year-old Sun holds the world record of the event in 14 minutes and 31.02 seconds and he has won two world titles as well as London Olympic gold medals in the long-distance event.