Badminton's former world No. 1 Lee Chong Wei lost to the current top-ranked shuttler Chen Long on Friday in Taipei, falling short in his stiffest test since returning to the sport in May after an eight-month ban for doping.
The Chinese beat the unseeded Malaysian 17-21, 22-20, 21-13 in the men's singles quarter-finals of the Chinese Taipei Open, slowing down the 32-year-old's bid to secure enough ranking points to qualify for the Rio Olympics in August next year.
Lee, whose world ranking has recovered to 65th after restarting competitive play in the Sudirman Cup in May, won the lower-ranked US and Canadian Opens last month.
Another former world No. 1, China's world No. 5 Lin Dan, remains on course to meet Chen in the final on Sunday. He beat unheralded Indonesian Anthony Ginting 21-7, 22-20 to enter the semi-finals.
