TOKYO- Women's world number one Li Xuerui pulled out of the Japan Open on Wednesday with a sore knee and men's number two Chen Long suffered a shock defeat to cap a miserable day for China. The withdrawal of Li, the top seed and London Olympic champion, from the eighth leg of the 12-round World Superseries was linked by her team-mate to a jam-packed competition schedule for Chinese players, with Chen also saying that he was fatigued.

Li's nearest rival and second seed Ratchanok Intanon of Thailand, who beat the Chinese at the world championship final in August, was also forced out the competition, suffering lower-back pain. The back problem had also sidelined the 18-year-old Thai from the China Masters last week. Chen, the All-England champion, went out 24-22, 21-16 to Kazuteru Kozai of Japan, ranked 287th in the world and with no major international success to his name. "What I need is to rest first of all," the 24-year-old Chen said through an interpreter. "I have fought week after week. But it's the same for the whole Chinese team. I am tired but it's just normal. I wish the Badminton World Federation will arrange a less tight schedule."

Chen, who lost to China's superstar Lin Dan in the world championship quarter-finals last month, also fell in the last eight at the Chinese National Games. He pulled out of the China Masters. The packed playing schedule has been a common concern for badminton stars, with Malaysian world number one Lee Chong Wei being advised to reduce his tournament appearances in order to continue his career toward the 2016 Rio Olympics.