Prague, Czech Republic (SportsNetwork.com) - Top-seeded Karolina Pliskova and No. 3 seed Barbora Strycova reached the quarterfinals, while their second- seeded fellow Czech Lucie Safarova exited the draw Wednesday at the Prague Open.

Pliskova overcame Bulgaria's Tsvetana Pironkova 3-6, 6-3, 7-6 (7-5), while Strycova handled Russian Elena Vesnina 6-3, 6-3 in second-round action at this clay-court event.

Meanwhile, Tereza Smitkova upset her fellow Czech Safarova 6-3, 2-6, 6-4 in opening-round action in Prague. Smitkova also played her second-round match on Wednesday, but lost to Czech Lucie Hradecka 6-3, 4-6, 7-6 (13-11). The 2011 Prague champion Hradecka, like Smitkova, also saw double duty on Day 3, as she opened her day with a first-round victory over Russian Anastasia Pavlyuchenkova, 6-1, 7-5.

A second-round upset came when Czech wild card Denisa Allertova doused fifth- seeded Frenchwoman Alize Cornet 3-6, 7-5, 6-2.

In other second-round play, qualifier Danka Kovinic of Montenegro drubbed Chinese Zhang Shuai 6-1, 6-4; Belgian Yanina Wickmayer held off Serb Aleksandra Krunic 7-5, 6-7 (3-7), 7-5; Czech Katerina Siniakova dismissed Slovenian Polona Hercog 6-1, 6-4; and Czech favorite Klara Koukalova edged out Croatian qualifier Ana Konjuh 6-4, 2-6, 6-2.

Thursday's quarterfinals will pit Pliskova against Allertova; the 2010 Prague runner-up Strycova versus Siniakova; the wild card Koukalova against the qualifier Hradecka; and Kovinic versus Yanina Wickmayer.