Top seeds Lee Hyun Il and Son Wan Ho remain on course for a finals showdown at the Thailand Masters after winning their respective quarter-finals on Thursday.
Lee faced the tougher quarter-final opponent in fifth seed Wei Nan of China, but the South Korean shuttler needed just 39 minutes to secure a 21-18, 21-13 victory.
Lee’s countryman and second seed Son faced another Korean in ninth seed Jeon Hyeok Jin, and had to battle back from a game down before prevailing 11-21, 21-12, 21-11.
Lee moves on to face local favourite Tanongsak Saensomboonsuk after the 12th seed upset sixth seed Ng Ka Long Angus of Hong Kong 21-15, 21-14.
Awaiting Son in the last four is Chinese third seed Hu Yun, who ended the run of India’s Sameer Verma with a 21-18, 21-12 victory.
There were no major upsets in the women’s draw, with the top seeds all advancing safely.
Second seed Ratchanok Intanon beat fellow Thai Nitchaon Jindapol 21-14, 21-14 to set up a semi-final meeting with South Korean third seed Sung Ji Hyun, who defeated another Thai, seventh seed Porntip Buranaprasertsuk 21-17, 21-10.
The other semi-final sees sixth seed Busanan Ongbumrungphan of Thailand take on fourth seed Sun Yu of China.
Ongbumrungphan was a 21-5, 21-18 winner over Dinar Dyah Ayustine, while Sun beat Yip Pui Yin 21-15, 21-9.