Ratchanok, the second seed, beat Supanida Katethong 21-11, 21-18 in a late match last night.
Rising star Kunlavut Vitidsarn also advanced but Thailand’s top men's player Kantaphon suffered an early exit at the BWF World Tour Super 300 event at Indoor Stadium Hua Mark.
Busanan held off sixth seed Sung Ji-Hyun of South Korea in a 26-24, 22-24, 21-18 thriller while Phittayaporn and Pornpawee had easier assignments, beating Lianne Tan of Germany 21-18, 21-12 and Fitriani Fitriani of Indonesia 21-9, 21-16 respectively.
Busanan will play Gregoria Tunjung of Indonesia, Phittayaporn will face top seed Akane Yamaguchi of Japan and Pornpawee will meet fourth seed Carolina Marin of Spain in the second round today (Jan 23).
Marin, runner-up to Ratchanok at the Indonesia Masters on Sunday (Jan 19), came through her first hurdle with a 20-22, 21-10, 21-5 victory over Kim Ga-Eun of South Korea.
Kunlavut, 18, advanced after a 21-14, 21-13 victory over Vladimir Malkov of Russia while Kantaphon, Thailand’s highest ranked male player at No.12, bowed out at the hands of compatriot Suppanyu Avihingsanon, who is ranked 35 places below him.
Suppanyu claimed the surprise 18-21, 21-12, 21-14 victory in 66 minutes and booked his second round berth against fellow Thai Khosit Phetpradab, who defeated Huang Yuxiang of China 14-21, 21-13, 21-14.
Jongkolphan Kititharakul and Rawinda Prajongjai eased past Anna Ching Yik Cheong and Lim Chiew Sien of Malaysia 21-7, 21-16 in the women’s doubles first round.