"I improved my under-water legs in the last few months when we trained in the United States, and I think that made me better," said Liu, who won a bronze medal from 50m backstroke in 2015 World Championships in Kazan.

Liu said she did not perform well in the morning heat with the under-water kicks. "My coach He Xinzhong told me to pay more attention on the legs and that helped me dominate the race from the start."

Liu will compete in 50m freestyle on Aug 24.

The 2015 world champion Fu Yuanhui took the silver medal in 27.68 and Sakai Natsumi of Japan placed third 27.91.

"I am happy for Liu Xiang. What a great thing that Liu carries the flag of the world record from our Chinese swimmers. For me, I recovered from my shoulder injury and I am now 70% in form," Fu said.