Fourth seed Ratchanok cruised past Yvonne Li of Germany 21-11, 21-15 to set up a quarter-final clash against An Se-Young of South Korea.
Seventh seed An eased past 15-year-old Sirada Roongpiboonsopit 21-8, 21-7 in the other second round match.
Earlier, Busanan survived a tough test against India’s Saina Nehwal, fighting back to beat the former world No.1 21-23, 21-14, 22-20 to reach the last eight.
Busanan will face Denmark’s Mia Blichfeldt, who defeated Iris Wang of the United States 21-12, 21-16.
“It was such a long match. In the first game I was a bit stiff, I hardly controlled myself. I lost some easy points, but I tried to concentrate and keep my game going as long as it could,” said Busanan.
“Nehwal is famous for her fitness, stamina and patience. She tried to force me into a running game. I needed to use all my strength to match her tough style. I played with more than 100% commitment to win every point,” said the Thai.
Supanida had a lot less trouble against Evgeniya Kosetskaya, beating the Russian 21-16, 21-8 in just 29 minutes.
“At the beginning, I was a bit under pressure because the last time that we played she beat me. In the second game, I tried to change my play and avoid any risks. I think I have learned a lot from this match. It’s a good experience for me,” said Supanida.
However next up for Supanida will be reigning Olympic champion Carolina Marin. The Spanish fifth seed eliminated another Thai hope Pornpawee Chochuwong 21-8, 21-12.
Top seed Tai Tzu-ying of Taiwan also advanced after beating Kim Ga-Eun of South Korea 21-16, 21-10.
Tai will play Michelle Li of Canada today after the eight seed defeated Sung Ji-Hyun of South Korea 21-17, 21-17.
There was no Thai players left in the men’s singles event after Kunlavut Vitidsarn, Kantaphon Wangcharoen and Khosit Phetpradab all lost yesterday.
Kunlavut was beaten by fifth seed Anthony Ginting of Indonesia 16-21, 19-21, Kantaphon fell to fourth seed Viktor Axelsen of Denmark 13-21, 17-21 and Rasmus Gemke of Denmark downed Khosit 22-20, 21-8.
Mixed doubles stars Dechapol Puavaranukroh and Sapsiree Taerattanachai progressed with a tough three-game win over Goh Soon Huat and Shevon Jemie Lai of Malaysia.
The top-seeded Thai pair dropped the first game 20-22 but battled back to win the next two 21-18, 21-12 to seal their last-eight berth.
“It was a very competitive game at the beginning, but later our team changed some tactics to move the game around the court which made them run more. That’s why we got an advantage of scoring the points.” said Sapsiree.
Dechapol added, “I think we were 90% in terms of our performance today because there were few mistakes along the way.”
Seventh seeds Jongkolphan Kittitharakul and Rawinda Prajongjai progressed in the women’s doubles event after beating Emilie Lefel and Anne Tran of France 21-9, 21-13.
Men’s singles second seed Chou Tien-chen of Taiwan cruised through with a 21-16, 21-19 win over Shesar Hiren Rhustavito of Indonesia.
“The shuttle today was a bit slow so we had many long rallies and he was quite strong and patient, so I had to be at 100% to defeat him,” said Chou.
The second-seeded Taiwanese will next play Malaysia’s Lee Zii Jia, who got a walkover win over India’s Srikanth Kidambi, who was forced to pull out with a right calf muscle strain.
The Yonex Thailand Open is the first of three consecutive tournaments in the Asian leg of the BWF World Tour held behind closed doors.
The tournament, which ends on Sunday, will be followed by the Toyota Thailand Open from Jan 19-24.
Both are Super 1000 tournament with a total purse of US$1mn each.
The season will conclude with the $1.5mn HSBC BWF World Tour Finals 2020 (Jan 27-31).