Top seed An Se-Young proved much too strong for Supanida Katethong as the South Korean comfortably beat the Thai 21-17, 21-9 in the quarter-finals of the US$420,000 Masters Japan in Kumamoto yesterday.
It was a bad day for Thailand as Supanida's compatriots all lost in the last eight to end the country's interest in the World Tour Super 500 event.
An, 21, needed just 42 minutes to finish off Supanida.
An, the reigning world and Asian Games champion, will next face Olympic champion Chen Yufei of China in the semi-finals.
Third-seeded Chen defeated fifth seed Carolina Marin of Spain 21-12, 21-9 in the quarter-finals.
Seventh seed Zhang Beiwen of the US takes on sixth seed Gregoria Mariska Tunjung from Indonesia in the other semi-final.
In the last eight, Zhang upset fourth seed Tai Tzu-ying of Taiwan who retired after trailing 6-0 in the third game.
Tunjung beat Singapore's Yeo Jia Min 22-20, 21-19.
In the women's doubles quarter-finals, top seeds Jongkolphan Kititharakul and Rawinda Prajongjai of Thailand were upset by home players Mayu Matsumoto and Wakana Nagahara 21-12, 21-18.
Thai sisters Benyapa and Nuntakarn Aimsaard were defeated by China's Liu Shengshu and Tan Ning 15-21, 21-16, 21-18.
In the men's singles, top seed Viktor Axelsen booked a place in the semi-finals after coming from behind to beat Indonesia's Jonatan Christie 15-21, 21-18, 21-9.