Mixed doubles pair Supak Jomkoh and Supissara Paewsampran booked their berth in the last 16 of the season-opening BWF Malaysia Open in Kuala Lumpur on Tuesday.
The Thai duo stunned fourth seeds Feng Yanzhe and Huang Dongping of China 22-20, 21-19 in the 43-minute first round match at Axiata Arena.
It was the 20th-ranked Thais' first victory in five meetings against the Chinese players.
They will next face Hee Yong Kai and Tan Wei Han of Singapore after the world No.22 pair rallied to overcome Ye Hong-wei and Lee Chia-hsin of Taiwan 15-21, 21-19, 21-12.
Another mixed doubles pair Dechapol Puavaranukroh and Sapsiree Taerattanachai also made it to the second round after they eased past Robin Tabeling and Selena Piek of Netherlands 21-15, 21-10.
They will play Malaysia's Goh Soon Huat and Shevon Jemie Lai in the last 16.
Earlier, women's singles hope Supanida Katethong exited the tournament in the first round.
The world No.16 lost to defending champion Akane Yamaguchi of Japan 15-21, 20-22.
Third seed Yamaguchi, who returned to action after the longest lay-off of her career, came through her first match in four months in 43 minutes.
The Japanese world No.3 was injured during the Asian Games in Hangzhou, China, in September last year.
Supanida briefly threatened to force a decider, leading 19-18 in the second game but Yamaguchi did just enough to avoid a longer tussle.
"It was a close match but I was able to stay calm. I didn't get nervous, that's a good sign," said Yamaguchi who faces Kirsty Gilmour of Scotland next.
Gilmour overcame Neslihan Arin of Turkey 21-23 21-14 21-13 in her opener.
In the other first round results, men's singles top seed Viktor Axelsen of Denmark cruised through his opener, beating Loh Kean Yew of Singapore 21-13, 21-5 while Srikanth Kidambi of India knocked out sixth seed Jonatan Christie of Indonesia 12-21, 21-18, 21-16.
Olympic champion Axelsen is looking to win the tournament for the third consecutive year.
Thai hopes Kunlavut Vitidsarn and Ratchanok Intanon, who is making a return after a long injury lay-off, will play their first round matches today.
The tournament offers a total prize money of US$1.3 million (approximately 44.2 million baht).