CARLSBAD, Calif. -- Poland's Ursula Radwanska took advantage of Jelena Jankovic's poor serving for a 6-2, 4-6, 6-3 victory Thursday in the second round of Southern California Open.
The sixth-seeded Jankovic, from Serbia, had seven double faults and was successful on only 59 percent of her first serves.
Radwanska advanced to the quarterfinals against top-seeded Victoria Azarenka of Belarus. It is just the fourth time this season Radwanska has reached the quarters.
Radwanska, ranked No. 39, has five top-20 wins this season after defeating Jankovic, ranked 16th.
Vandeweghe, from nearby Rancho Santa Fe, won five consecutive points to take a 5-2 lead in the first set tiebreaker. Ivanovic then reeled off the final five points, including a crosscourt forehand winner to win the set.
Ivanovic jumped out to a 4-0 lead in the second set before needing four match points to advance to the quarterfinals against fourth-seeded Roberta Vinci.
Wild-card entrant Virginie Razzano of France also advanced with a 6-1, 6-4 victory over eighth-seeded Carla Suarez Navarro of Spain. Razzano, who beat two-time Grand Slam singles champ Svetlana Kuznetsova of Russia in the first round, will face third-seeded Petra Kvitova of the Czech Republic.
Hantuchova, who is teaming with former top-ranked singles player Martina Hingis in doubles, has lost to Agnieszka Radwanska in the tournament three of the last four years.