Top-seeded Petra Kvitova had to dig deep to reach the second round of the Bad Homburg Open in beating Polish qualifier Katarzyna Piter 4-6, 6-1, 6-4. Kvitova lost serve three times but hit 10 aces while prevailing against 135th-ranked Piter in just under two hours at the Wimbledon warmup.
Two-time Wimbledon champion Kvitova, who's ranked 12th, will next play American Ann Li, who eased past Germany's Anna Zaja 6-0, 6-4.
Another American, Jessica Pegula, also had little difficulty as she got past French player Amandine Hesse 6-2, 6-1. The third-seeded Pegula next faces Czech player Katerina Siniakova. Also, there were wins for Alizé Cornet, Laura Siegemund, Sara Sorribes Tormo and Anna Blinkova.
Simona Halep pulled out of the grass-court tournament shortly before it started in the town near Frankfurt.
