BAOJI, China - Olympic and world champion Liu Zige only managed a seventh finish in her signature women's 200-meter butterfly at the National Swimming Championships here on Monday.

Liu Zige of China prepares to compete during the Women's 200m butterfly semi-finals on day four of the China National Swimming Championships on April 12, 2015 in Baoji, Shaanxi province, China. [Photo/CFP]

The reigning world champion timed two minutes 11.90 seconds to rank seventh, while Zhou Yilin of Hebei won the title in 2:08.02, eighth in the global ranks this season. Jiangsu's Zhang Yufei came second in 2:08.32, and Henan's Li Shuang placed third in 2:08.67.

"I don't think I can take part in the World Championships," said Liu, who won the 200m fly at the Beijing Olympic Games and renewed the world record to 2:01.81 at the National Games in 2009. "I'm out of strength in the last meters. I am so tired."

"But I will keep training, and see what happens next year," added the 26-year-old, who withdrew from the 100m fly at the Nationals.

London Olympic champion Jiao Liuyang didn't take part in the butterfly events and will only compete in the 50m freestyle on Thursday.

Without the two famed butterfly specialists, China may lose its force in the 200m fly at the Kazan worlds.

Zhejiang swimmer Wang Shun rose to third in the world this year with a 1:58.13 finish in the men's 200m individual medley. Yang Zhixian of Hunan came in second in 1:59.50 ahead of his teammate, Huang Chaosheng, 1:59.82.

In the women's 50m backstroke, Zhejiang's 19-year-old Fu Yuanhui, runner-up of the 2013 Barcelona Worlds, touched in first in 27.61, a world third fastest time so far this year. Liu Xiang of Guangdong took silver in 27.87, slower than her semifinal time 27.73, which was fourth in global ranks. Hubei's Chen Jie came third in 28.37.

The men's 100m free final was dominated by Asian champion Ning Zetao, who touched in first in 48.36, 0.02 seconds more than his semifinal time. Guangdong's Yu Hexin trailed in 49.11 while Liaoning's Lin Yongqing and Jiangsu's Xu Qiheng both ranked third in 49.86.

Ning Zetao poses with his men's 100m freestyle gold medal at the China National Swimming Championships on April 13, 2015 in Baoji, Shaanxi province, China.  [Photo/CFP]

"I am more relaxed than yesterday," said the 21-year-old Ning. "It is my first competition this year and there are lots of things to be improved. I hope I can make the final at the Worlds."

Also on Monday, team Beijing won the women's 4x200m freestyle relay in 8:04.48, ahead of Liaoning, 8:08.02 and Shanxi, 8:09.48.