Third seed Busanan Ongbamrungphan and fourth seed Nitchaon Jindapon both progressed to the last four at the Nimibutr Stadium and are kept apart in the semi-finals.

Ongbamrungphan had to come from behind to oust Liang Xiaoyu of Singapore, 20-22, 21-13, 21-12.

Passage through was more comfortable for Jindapon, however, who defeated Dinar Dyah Ayustine of Indonesia 21-12, 21-15.

The reward for Ongbamrungphan is a semi-final with Goh Jin Wei of Malaysia, a 21-17, 21-13 winner over her compatriot Ho Yen Mei today.

Jindapon will play Japan's Aya Ohori, who eased past Malaysia's sixth seed Tee Jing Yi 21-13, 21-6.

In the men's tournament, Thai success is also on the cards in the Grand Prix Gold level event.

Home hopes rest with Tanongsak Saensomboonsuk, a 21-8, 21-18 victor in his quarter-final against compatriot Suppanyu Avihingsanon.

He will now play Japan's Kenta Nishimoto who got the better of Chinese Taipei's Hsu Jen-hao, 21-16, 21-11.

Indonesia's second seed Sony Dwi Kuncoro is the top-ranked player left in the competition, after he beat Hsueh Hsuan-yi of Chinese Taipei 21-12, 21-15.

His next opponent will be Hong Kong's Lee Cheuk Yiu, who came through against Malaysian Daren Liew 21-12, 17-21, 21-15.

Action in the Thai capital continues tomorrow with the last four contests.