ANTWERP, Belgium -- Third-seeded Andrea Petkovic of Germany advanced to the Diamond Games semifinals Friday after beating sixth-seeded Slovakian Dominika Cibulkova 7-6 (2), 6-0 in a scrappy match featuring 11 breaks of serve.
Both players dropped serve four times each in a wobbly first set, but Petkovic tightened up her game in the second set, where she did not allow a break point and broke Cibulkova's serve on all three opportunities.
Petkovic next faces Czech player Barbora Zahlavova Strycova, who broke German player Mona Barthel's serve five times in a 6-2, 6-2 win. Neither player managed an ace.
Earlier, fifth-seeded Carla Suarez Navarro of Spain and eighth-seeded Karolina Pliskova of the Czech Republic won their matches to set up a semifinal meeting.
Suarez Navarro saved 10 break points in a 6-3, 6-2 quarterfinal win against former French Open champion Francesca Schiavone of Italy, who dropped her serve five times.
Pliskova defeated fourth-seeded countrywoman Lucie Safarova 7-6 (5), 6-3.
Both players hit eight aces each, while Pliskova saved four break points and broke Safarova's serve at the first opportunity in the second set.
