Top-seeded Venus Williams was an easy straight-set winner over Magadalena Rybarikova during Thursday's quarterfinals at the inagural WTA Brasil Tennis Cup.

One day after being taken to the limit by Spanish teen Garbine Muguruza in a three-set thriller in the second round, the seven-time Grand Slam champion Williams had little problems disposing of the fifth-seeded Rybarikova in 6-4, 6-0 fashion on the hardcourts at Federacao Catarinense de Tenis.

Williams' victory sets up a semifinal bout with Olga Puchkova on Friday after the unseeded Russian routed Slovakia's Jana Cepelova by a 6-1, 6-1 score in just 75 minutes.

Seventh-seeded French teenager Kristina Mladenovic also reached the semis by handling Hungarian Melinda Czink 6-4, 6-3, while Romanian Monica Niculescu routed Hungary's Timea Babos 6-3, 6-2. The 19-year-old Mladenovic will battle Niculescu in Friday's other semifinal.