Women's world champion badminton player Ratchanok Intanon was eliminated from the OUE Singapore Open on Friday, losing 14-21, 12-21 to China's Han Li in the quarter-finals.
The Thai world No. 4 never looked like she was in control of the match, and made many unforced errors against her world No. 17 opponent.
Intanon later said a recent injury from the All England Championships last month had contributed to her loss. This is the first tournament she is taking part in since suffering a calf injury then, and has not been able to train.
"My opponent came prepared today to give me a good fight. She kept attacking my weak spots," Intanon said after her defeat.
In the men's doubles, Indonesia's Mohammad Ahsan and Hendra Setiawan were also booted out after going down 15-21, 21-13, 19-21 to South Korea's Kim Sa Rang and Yoo Yeon Seong.
The Koreans will play China's Cai Yun and Lu Kai in the semi-finals next.
Three of the four semi-finalists on Saturday are from China, with Han playing team-mate Wang Yihan while Li Xuerui will clash with South Korea's fifth seed Sung Ji Hyun.
Men's world No. 1 Lee Chong Wei of Malaysia beat Thailand's Tanongsak Saensomboonsuk 21-8, 21-14 in their quarter-final. Lee will play India's K. Srikanth next.
The Chinese team withdrew two doubles pairs from the competition. Men's doubles Chai Biao and Hong Wei handed a walkover to Ko Sung Hyun and Shin Baek Choel after Hong came down with acute skin rashes.
In the mixed doubles, Xu Chen and Ma Jin withdrew due to Xu's thigh strain. Indonesians Riky Widianto and Puspita Richi Dili proceed to the semi-finals.