Du Pengyu, the Chinese world No. 3, became the latest big name to crash out of the Li-Ning Singapore Open badminton tournament on Thursday.
He lost to 18-21, 21-12, 19-21 Germany's Marc Zwiebler.
Team-mate Wang Zhengming, last year's runner-up and world No. 9, was beaten 21-16, 22-20 by Indonesia's world No. 13 Tommy Sugiarto.
The competition also lost the women's defending champion earlier on Thursday when German Juliane Schenk was beaten 21-19, 21-15 by China's Sun Yu.
Reigning mixed doubles Olympic champions Zhang Nan and Zhao Yunlei of China were also beaten 21-15, 23-21 by South Korea's world No. 35 Ko Sung Hyun and Kim Ha Na.