World No.5 Ratchanok eased past Busanan 21-4, 21-16 in her opening Group B match at Tianhe Gymnasium. It was Ratchanok's seventh successive win over her 16th-ranked compatriot.
Ratchanok will next play top-ranked Tai Tzu-ying of Taiwan, while Busanan will meet Japan's world No.3 Nozomi Okuhara.
Okuhara and Tai engaged in a tough opening match last night, with the Japanese coming out on top with a 15-21, 21-18, 21-19 victory in 61 minutes.
Mixed doubles stars Dechapol Puavaranukroh and Sapsiree Taerattanachai also got off to a triumphant start, beating Seo Seung-Jae and Chae Yu-Jung 21-16, 21-19 in their opening Group A match.
The victory ended a run of three straight losses against the South Koreans, and Dechapol and Sapsiree have now evened their head-to-head record at 3-3.
Dechapol and Sapsiree will play Malaysia's Chan Peng Soon and Goh Liu Ying in the second group match today.
After six straight losses, Jongkolphan Kititharakul and Rawinda Prajongjai came within a whisker of an upset over world champions Mayu Matsumoto and Wakana Nagahara of Japan in the women's doubles Group B clash.
The Thais held match point before the Japanese got the better of them, 19-21 21-14, 22-20.
They will face Kim So-Yeong and Kong Hee-Yong in the second match. Kim and Kong also lost their opener, falling to fellow Koreans Lee So-Hee and Shin Seung-Chan 21-18, 17-21, 18-21.
The men's singles Group B, labelled ‘the group of death,’ lived up to its billing with two riveting matches yesterday.
Chen Long and Chou Tien Chen emerged winners over Viktor Axelsen and Anthony Ginting respectively, but the effort had taken them over an hour and 10 minutes each.
Matches between Axelsen and Chen have often been hard-fought.
And yesterday was no exception as the Chinese needed three games to overcome his Danish opponent 21-17, 10-21, 21-17.
The contest between Chou and Ginting was equally entertaining.
Ginting worked hard to stave off four match points in the third game but Chou refused to get frustrated and kept up the pressure with his attack, taking the match 11-21, 21-15, 25-23.