Rising star Kunlavut Vitidsarn joined Thai compatriot Ratchanok Intanon in the last 16 of the BWF World Championships in Tokyo on Wednesday.
Men's singles star Kunlavut, the 16th seed, defeated Kodai Naraoka 21-18, 21-11 in the second round and will play Kenta Nishimoto, another Japanese, in the last 16 round.
Women's singles eighth seed Ratchanok, the 2013 world champion, defeated fellow Thai Phittayaporn Chaiwan 21-17, 21-17 to set up a last-16 clash against Canadian 13th seed Michelle Li.
Another Thai hope Pornpawee Chochuwong, who is seeded 10th, also advanced after she beat Sim Yu-Jin of South Korea 18-21, 21-16, 21-10.
Pornpawee will face Tokyo Olympic champion and fourth seed Chen Yufei of China in the last 16.
Thailand's Busanan Ongbamrungphan progressed after fighting back to beat Yvonne Li of Germany 20-22, 21-16, 22-20.
She will play India's Saina Nehwal in the third round on Thursday.
Defending mixed doubles champions Dechapol Puavaranukroh and Sapsiree Taerattanachai also won their second-round match.
The second-seeded Thais advanced with a 21-11, 21-18 victory over Choi Sol-Gyu and Shin Seung-Chan of South Korea.
They next face ninth seeds Mark Lamsfuss and Isabel Lohau of Germany.
In the women's doubles event, seventh seeds Jongkolphan Kititharakul and Rawinda Prajonghai of Thailand defeated Siti Fadia Silva Ramadhanti and Ribka Sugiarto of Indonesia 21-15, 10-21, 21-15.
Thailand's 14th seeds Puttita Supajirakul and Sapsiree beat Margot Lambert and Anne Tran of France 22-20, 21-18.
However, Thais Benyapa Aimsaard and Nuntakarn Aimsaard bowed out after they lost to sixth seeds Mayu Matsumoto and Wakana Nagahara of Japan 21-17, 21-18.
Kunlavut gave a nice exhibition of skill and control as he denied home hope Naraoka in two games.
Kunlavut, who beat Naraoka in the final of the World Junior Championships 2018, came away pleased with his efforts after the 70-minute match.
"Today I could control the shuttle and I didn't make any mistakes. I'm happy because I could control everything on court," said Kunlavut.
"The shuttle was very slow and as it's a big stadium, there was drift. I cannot control the shuttle when I move fast and play fast.
"To control the shuttle I had to play slow first, and then sometimes change my pace. If you attack too much, you get tired, because the shuttle is slow."
Meanwhile, Japanese Kento Momota bowed out of the championships after losing to HS Prannoy of India 21-17, 21-16.
India's Commonwealth Games badminton bronze medallist Srikanth Kidambi was stunned by unseeded Zhao Junpeng in the second round.
The 12th seeded Srikanth, the silver medallist at last year's world championships, lost 21-9, 21-17 to China's Zhao, his second-game comeback falling away at the finish.
Srikanth, part of India's Thomas Cup-winning team in May, said he "could have played better" but was not as clinical as his opponent.
"He just played well when it really mattered," said the former world No.1. "I had my chances in the second set and if I had won it, anything could have happened in the third set.
"It's just about winning the points when it really matters."
In other men's singles results, Malaysian fifth seed Lee Zii Jia sealed an easy 21-9, 21-3 win over Bernardo Atilano of Portugal while ninth seed Lakshya Sen of India defeated Luis Enrique Penalver of Spain 21-17, 21-10.
