Top-seeded Roberta Vinci secured a berth in the semifinals at the $220,000 Estoril Open tennis event.

The Italian Vinci held off seventh-seeded former top-10 star Nadia Petrova of Russia 6-2, 1-6, 6-4 in 1 hour, 46 minutes at National Stadium.

Vinci's semifinal opponent on Friday will be sixth-seeded Estonian slugger Kaia Kanepi, who bounced fourth-seeded Czech Petra Cetkovska 6-3, 3-6, 6-3 in 2 hours, 18 minutes on Day 4.

Two other quarterfinal bouts saw Carla Suarez Navarro dismiss fellow Spaniard Silvia Soler-Espinosa 6-3, 6-3 and Italian qualifier Karin Knapp sneak past Kazakhstan's Galina Voskoboeva 7-6 (7-4), 2-6, 6-4. Suarez Navarro and Knapp will do battle in the other semi.

The winner of this clay-court French Open tune-up will take home $37,000.