Yaroslava Shvedova is the only seed left in her half of the Hua Hin Championships draw after Zheng Saisai and Kurumi Nara crashed out on Thursday.
Shvedova - seeded fourth in Thailand - was made to battle in the opening set by Liu Chang, but having edged the tie-break she dominated the second set to progress 7-6 (7-4) 6-4.
The 28-year-old's victory sets up a quarter-final clash against Duan Ying-ying after she beat fifth seed Nara 6-4 4-6 6-1.
Heading into the second round Zheng was the highest ranked player left in the competition after Misaki Doi's early exit, but she too saw her tournament ended prematurely.
After losing the opening set to Hsieh Su-wei, Zheng battled back to take their match to a decider, but was unable to maintain that momentum, eventually losing 6-1 2-6 6-2 in just under two hours.
The final match of the round saw Wang Yafan meet Wang Qiang and it was the latter who booked a quarter-final spot against Hsieh with a 6-3 6-1 win.