Ratchanok Intanon will battle arch-rival Akane Yamaguchi for the Denmark Open title in Odense on Sunday.
The Thai world No.9 stunned top seed and world No.1 Tai Tzu-ying of Taiwan 21-14, 20-22, 21-14, while defending champion Yamaguchi of Japan battled back to defeat Chen Yufei of China 10-21, 21-18, 21-19 in Saturday's semi-finals.
The victory was a sweet revenge for Ratchanok, who put an end to a string of three successive defeats to the Taiwanese to book her berth in the final of the US$750,000 (26 million baht) BWF Superseies Premier tournament.
Ratchanok's last three losses against Tai came at the Australian Open in June, the All England Open in March and the Dubai World Series Finals in December last year.
Ratchanok, 22, has been in impressive form this week. She did not drop a game before yesterday's semi-final.
She knocked out third seed Sung Ji-Hyun of South Korea 21-13, 21-18 in the quarter-finals on Friday.
Earlier, holder Yamaguchi, who beat Tai in the title match last year, registered her fourth win in five meetings against the reigning junior world champion Chen.
In the men's singles semi-finals, South Korea's Lee Hyun-Il defeated top seeded compatriot and world No.2 Son Wan-Ho 25-23, 18-21, 21-17 in a 92-minute thriller.
Lee, who knocked out defending champion Tanongsak Saensomboonsuk of Thailand in the second round, faces either Vincent Wong Wing Ki of Hong Kong or eighth seed Srikanth Kidambi of India in today's final.
In the mixed doubles, eighth seeds Tang Chun Man and Tse Ying Suet of Hong Kong upset third seeds Ahmad Tontowi and Natsir Liliyana of Indonesia 21-16, 21-18.
They play top seeds Zheng Siwei and Chen Qingchen in the final after the Chinese pair beat Malaysia's Goh Soon Huat and Shevon Jemie Lai 21-16, 21-16.
Lee So-Hee and Shin Seung-Chan defeated seventh seeds Chang Ye-Na and Jung Kyung-Eun, also from South Korea, 21-9, 22-20 in the first semi-final of the women's doubles.
