Vera Zvonareva won her 12th straight match at the Pattaya Open by beating Thai qualifier Nungnadda Wannasuk 6-1, 7-5 in the second round on Thursday.
The two-time defending champion won the first four games before Wannasuk shook off the nerves and held serve for the first time.
Zvonareva reeled off the next two games to take the opening set, and then took a 5-1 lead in the second before Wannasuk battled back to level it at 5-5.
Zvonareva regained her concentration to take a 6-5 lead and the 21-year-old Wannasuk double-faulted twice in the final game for the No. 3-ranked Russian to complete the win in 76 minutes.