World number one Li Xuerui pulled out of the Japan Open yesterday because of a sore knee, with her teammate linking the problem to a jam-packed schedule for Chinese players.
The 22-year-old London Olympic champion suffered pain in her left knee and consulted the venue doctor before the Japan Open's first day, a tournament press official said.
The doctor confirmed Li's knee trouble and the top-seeded Chinese player withdrew from the first-round match against Japan's Aya Ohori, the official said.
Li's male teammate Wang Zhengming said: "Members of the Chinese team, including myself, have a tight schedule filled with matches.
"I think she probably had an old injury that was hurting again somewhat because of fatigue," he said.
Li, beaten by Thailand's Ratchanok Intanon in the world championship final in Guangzhou in August, also lost to another Thai, Porntip Buranaprasertsuk, in the semi-finals of last week's China Masters.
Between the two international contests, Li also played in the Chinese National Games in Liaoning, claiming the women's gold medal.