PARIS — Andrea Petkovic of Germany upset fifth-seeded Aravane Rezai of France 6-3, 3-6, 6-3 on Thursday to advance to the quarterfinals at the Open GDF Suez.

Petkovic will next face top-seeded Elena Dementieva.

"She played well. I played well ... I am very happy," Petkovic said.

Shahar Peer defeated Croatia's Karolina Sprem 6-4, 6-3. The sixth-seeded Israeli will play Lucie Safarova of the Czech Republic, who defeated seventh-seeded Francesca Schiavone of Italy 7-5, 6-2.

Agnes Szavay beat Croatia's Petra Martic, 6-2, 6-4. The Hungarian will face American teenager Melanie Oudin, who beat Patty Schnyder of Switzerland 6-1, 6-3.