Porntip Buranaprasertsuk on Friday stunned third seed Wang Yihan of China 21-16, 18-21, 21-16 in the quarter-finals of the China Open badminton tournament in Shanghai.
In today's semi-finals, Porntip, the only Thai left in the event, will face seventh seed Wang Shixian of China in the top-tier Superseries tournament.
Porntip, 22, is chasing her second Superseries title after her win in India in 2011.
She has also won the Vietnam Open in 2012.
Wang Shixian beat world champion Ratchanok Intanon 24-22, 21-10 in the quarter-finals.
World No.2 Ratchanok has been less than convincing and plagued with injury problems since winning the world title in Guangzhou in August.