Wozniacki, Zvonareva win in Stuttgart
Top-ranked Caroline Wozniacki passed the Porsche Grand Prix second round for the first time when she beat Zuzana Kucova of Slovakia 6-1, 6-2 to reach the quarterfinals on Wednesday.
Wozniacki's bid for a fourth title this year set her up against Andrea Petkovic of Germany, who rallied to defeat former No. 1 Jelena Jankovic 3-6, 6-1, 6-3.
Petkovic, rapidly becoming a star in Germany, beat both Wozniacki and Jankovic in reaching the semifinals in Miami and broke into the top 20 for the first time.
She and Jankovic played a match filled with errors. Jankovic, serving poorly throughout, committed her sixth double-fault to give Petkovic a chance to serve out the match.
The German needed five match points to close it out.
''I was exhausted, but I couldn't lose, I hate losing more than I love winning,'' Petkovic said. ''I think I have a small chance tomorrow.''
Kucova, plucked from qualifying after Yanina Wickmayer withdrew with an injured knee, broke Wozniacki's serve once but struggled to hold her own.
After 10 years without a German player in the Stuttgart quarterfinals, there are four in the last eight this year.
Julia Goerges completed the quartet when fourth-seeded Victoria Azarenka had to withdraw from their second-round match with a right shoulder injury after winning the first set 6-4.
Women's tennis in Germany is going through a revival following a long slump that came after the retirement of Steffi Graf. Germany beat the United States 5-0 at the weekend in the same arena to seal a place in next season's Fed Cup World Group.
Sabine Lisicki and Kristina Barrois were the other home winners on Wednesday. Lisicki downed Australian Open runner-up Li Na 6-4, 7-5, and Barrois defeated eighth-seeded Marion Bartoli 6-4, 6-2.
Barrois landed 81 percent of first serves against the 12th-ranked Bartoli, the highest-ranked player she has beaten.
''I was a total outsider,'' said the 79th-ranked Barrois. ''This is a great success for me.''
Lisicki broke to lead 6-5 in the second set and served out the match against the sixth-seeded Chinese. The German was once ranked as high as No. 22, but was out for nearly half a year with an injured left ankle and has dropped to No. 155.
Like Barrois, Lisicki needed a wild-card entry for the tournament.
Lisicki will play Goerges in the quarterfinals, while Barrois meets Agnieszka Radwanska of Poland, who beat French Open champion Francesca Schiavone 6-1, 6-3.
Also in the second round, Vera Zvonareva rallied to beat Anastasia Pavlyuchenkova 3-6, 6-4, 6-2 in an all-Russian match.
The second-seeded Zvonareva remains on course to add to her Doha title this year after struggling past Pavlyuchenkova on the indoor clay court at Porsche Arena.
Zvonareva next faces last year's runner-up Sam Stosur, who beat Daniela Hantuchova 6-4, 2-6, 6-4.