Unseeded Maria Sakkari of Greece upended No. 1 seed Elina Svitolina of Ukraine 6-3, 6-3 on Wednesday to reach the JT Banka Ostrava Open quarterfinals in the Czech Republic.
Sakkari struck six aces, blasted 32 winners and converted five of her nine break chances against Svitolina, who won just 27.6 percent (8 of 29) of her second-service points.
In a first-round match, Latvia's Jelena Ostapenko breezed to a 6-3, 6-1 upset of No. 5 seed Petra Martic of Croatia in just 58 minutes.
"I didn't give her any chances to play her game, and I made so many winners," said Ostapenko, the 2017 French Open champion. "I played very smart and also used drop shots and mixed it up a little bit, which helped me, but in the deciding moments I was still very aggressive."
Also Wednesday, No. 4 seed Victoria Azarenka of Belarus rallied for a 2-6, 6-2, 6-1 win over Barbora Krejcikova of the Czech Republic, No. 7 seed Elise Mertens of Belgium posted a 6-2, 6-3 win over American Amanda Anisimova, and Spain's Sara Sorribes Tormo knocked out No. 8 seed Anna Kontaveit of Estonia 6-1, 6-4.
--Field Level Media