Shahar Pe'er moved into the quarterfinals in Memphis on Wednesday, surviving a second round scare to defeat Hungarian Melinda Czink 6-0, 3-6, 6-2. The 20-year-old Israeli, who is seeded third in the event, won the first eight games on Wednesday, but lost eight of the next nine games, giving Czink a 2-0 lead in the third set. Pe'er (18), however, regained her composure just in time and reeled off the next six games to book a last eight meeting against Swede Sofia Arvidsson (71). After claiming the first set in just 27 minutes Pe'er took the first two games of the second set and seemed to be strolling to a win. Czink (149), however, found her rhythm as the second set progressed and broke in the ninth game to tie the match. The Hungarian broke once more in the second game of the decisive set to open a 2-0 lead, but two consecutive love games by the Israeli renewed her stranglehold on the match and she quickly wrapped up the victory. Pe'er is the highest remaining seed in the tournament after the No. 1 and No. 2 seeds were knocked out in the first round late Tuesday. Top seed and defending champion Venus Williams (8) was upset in the opening round of the event by qualifier Petra Kvitova 2-6, 6-4, 6-3. The 17-year-old Kvitova earned only the second WTA Tour win of her career, stunning Williams, the winner of four Wimbledon titles. "I am very happy," said Kvitova. "It is the biggest [moment] of my life." Williams followed the No. 2 seed, Tatiana Golovin (13), out of the tournament. Earlier, Golovin was beaten by American Bethanie Mattek 6-4, 6-4. After winning the second set, Kvitova took charge midway through the final set. In the fifth game, she had two break points against Williams. Williams saved the first one with a forehand winner, but Kvitova recovered and followed with a forehand volley winner to go up 3-2. She closed the match with another break, sending a forehand volley winner past Williams before a stunned crowd. "She had a good serve and she was left-handed," Williams said. "She mixed it up really well. I'm not happy about the result of the match, but she played well." Playing in only her 14th career WTA match, Kvitova, ranked 143rd, matched Williams's power with punishing groundstrokes of her own. Williams was hampered by six double faults, including five in the second set. "I just made some mistakes," Williams said. "I definitely had more errors than I wanted." In the other upset, Mattek, ranked 131st, played one of the best matches of her career. "Honestly, I was really seeing the ball really well and I was there to every shot she hit," Mattek said. "I just stuck to my game plan. My goal was to get on top and get as many points right away as I could. I just came out firing." AP contributed to this report.