Sun Yang celebrates after winning the men's 400m freestyle at the Chinese National Swimming Championships in Qingdao, Shandong province, April 10, 2017. [Photo/Xinhua]

QINGDAO, China - World champion Sun Yang won the men's 400m freestyle with the world's best time of the year at the Chinese National Swimming Championships on Monday.

Sun, 25, met no challenge in the event as he touched home first in the opening final of the championships in three minutes and 42.16 seconds, the fastest time of the year in the world.

"The timing is satisfying," said Sun, who competed in his first event nearly eight months after the Rio Olympic Games, where the two-time world champion finished second after Australian Mack Horton in the 400m freestyle.

"I keep my eyes open for the ongoing Australian National Championships and I will try my best to outpace these swimmers," said Sun. His timing on Monday beat Horton's winning mark in Australia by 2.02 seconds. "All of us are preparing for the World Championships."

After Sun's triumph, Yan Zibei became the first swimmer to break a national record at the Championships as the 21-year-old finished first in 58.92 seconds in the semifinals of the men's 100m breaststroke.

"I went all out this evening," said Yan, representing Team Hubei. "I did think about breaking the national record but I never thought I could swim in 59 seconds this time."

In other actions, Li Bingjie from Team Hebei won the women's 400m freestyle in four minutes and 10.52 seconds.

Olympic medalist Fu Yuanhui led Team Zhejiang to clinch the women's 4x100m freestyle relay title in three minutes and 39.15 seconds. But their male teammates failed to win their relay due to the absence of Sun Yang, and Team Guangdong placed the first in three minutes and 18.14 seconds.