Jessica Pegula advanced to the quarterfinals of the Bett1Open in Berlin by defeating No. 4 seed Karolina Pliskova of the Czech Republic 7-5, 6-2 on Thursday.
Pegula converted six of her nine break-point opportunities and won 24 of 38 first-serve points to take care of her higher-ranked opponent in one hour and 15 minutes. She will face No. 7 seed Victoria Azarenka of Belarus in the next round after the two-time Grand Slam winner swept Germany's Angelique Kerber 6-3, 7-5.
In other action, No. 6 seed Garbine Muguruza of Spain -- another two-time Slam winner --dispatched Kazakhstan's Elena Rybakina 6-4, 6-3, and Russia's Liudmila Samsonova beat countrywoman Veronika Kudermetova 6-4, 6-3.
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No. 2 seed Ons Jabeur of Tunisia survived an upset bid and defeated Canadian Leylah Fernandez, 6-4, 3-6, 7-6 (3) in a match that lasted two hours and five minutes.
Fernandez saved three of four break points in the third set to hang around, but Jabeur won five straight points in the tiebreaker to get away.
No. 5 seed Jelena Ostapenko of Latvia wasn't as fortunate, as Tereza Martincova of the Czech Republic defeated her 7-6 (4), 4-6, 6-2. No. 4 Daria Kasatkina of Russia defeated Marta Kostyuk of Ukraine 6-2, 7-5, and Russia's Anastasia Potapova swept Frenchwoman Kristina Mladenovic 6-3, 6-3.
--Field Level Media