Top seed Sara Errani survived a nightmare second set to overcome local qualifier Melinda Czink and book her place in the quarter-finals of the Budapest Grand Prix in Hungary.
The in-form Italian started well against Czink, securing a double break in the first set before collapsing in the second and finally rallying to win 6-4 1-6 6-1 in one hour and 44 minutes.
The victory extended her winning streak on clay to 12 matches, the 25-year-old having already won titles in Acapulco and Barcelona on the surface this season.
Second seed Ksenia Pervak was well beaten 6-2 6-3 by Elena Vesnina, of Russia.
Sixth seed Petra Martic beat Su-Wei Hsieh 6-4 6-1, while Marina Erakovic, seeded five, progressed when Akgul Amanmuradova was forced to retire with an elbow injury having lost the first set 6-0.
The quarter-final line-up is completed by Alberta Brianti, Anna Tatishvili, Aleksandra Wozniak and Barbora Zahlavova Strycova, the latter having accounted for fourth seed Klara Zakopalova 6-3 6-3.