Home hope Luksika Kumkhum booked her place in the second round of the Hua Hin Championships after coming from one set down to defeat eighth seed Kirsten Flipkens 5-7 7-5 6-4.
The 211th-ranked Thai was broken three times as she lost the first set, but fought back valiantly with a series of strong service games sending the Belgian - placed some 118 positions above Kumkhum - packing in the opening round.
Seventh seed Timea Babos fell to an early exit, defeated by China's Wang Yafan, who she also lost to in qualifying for the China Open earlier this year, after failing to win any of the four break points that came her way in the second set.
Nao Hibino made light work of the United States' Alexa Glatch by winning 6-1 6-3 in just over an hour after, while Japan's Kurumi Nara also cruised into the second round with a comfortable 6-2 6-4 win over Zhang Kai-Lin.
Zheng Saisai is the highest seed remaining in the competition after she eased past Lu Jia-Jing into the second round, while Patricia Tig advanced when Zhu Lin retired after just over 40 minutes.
Wang Qiang, Hsieh Su-Wei and Liu Chang also advanced.