Second seed and defending champion Anna Karolina Schmiedlova suffered a straight-sets loss to Pauline Parmentier in the first round of the Katowice Open.
In a match that lasted under an hour, Schmiedlova produced five double faults as her unranked French opponent pulled off a 6-2 6-0 success.
Fifth seed Camila Giorgi was struggling too until she fought back from a set down in the second round to progress to a quarter-final meeting with Kirsten Flipkens.
The Italian was broken twice in losing the first set to qualifier Ekaterina Alexandrova before rallying to secure a 4-6 6-2 6-4 victory in two hours and 15 minutes.
Belgian Flipkens made far more serene progress as she swatted aside Romanian Andreea Mitu 6-1 6-2.
Latvian Jelena Ostapenko, the third seed who defeated Daniela Hantuchova on Tuesday, beat Kristyna Pliskova 6-3 6-4 while Timea Babos and Dominika Cibulkova also won in straight sets against Jesika Maleckova and Elizaveta Kulichkova respectively.
British doubles players experienced mixed fortunes in the doubles, with Heather Watson and her Polish partner Klaudia Jans-Ignacik being eliminated by the French pair of Stephanie Foretz and Amandine Hesse.
However, Naomi Broady and Polish player Alicja Rosolska advanced to the semi-finals having won their first-round match and learned that second-round opponent Karin Knapp's injury meant they had progressed straight through to the last four.
Source: PA
