Tokyo, Japan (My Sportsbook) - Former world No. 1s Jelena Jankovic and Maria Sharapova were among Wednesday's third-round winners at the $2 million Pan Pacific Open.

The seventh-seeded Jankovic was leading Elena Vesnina 6-1, 3-0 when the Russian retired, citing a left thigh strain, on the hardcourts at Ariake Colosseum. The Serbian Jankovic's quarterfinal opponent on Thursday will be 14th-seeded Frenchwoman Marion Bartoli, a 4-6, 6-2, 7-5 winner against Russian qualifier Anastasia Pavlyuchenkova on Day 4.

The unseeded 2005 Pan Pacific Open titlist Sharapova, meanwhile, came from behind to beat fellow Russian Alisa Kleybanova 2-6, 6-2, 6-2. Up next for the three-time major champion will be Czech Iveta Benesova, who handled qualifier Kai-Chen Chang, of Taipei, 7-5, 6-2.

In other third-round action involving seeds, No. 8 Belarusian Victoria Azarenka topped Czech Lucie Safarova 7-5, 6-4, No. 11 Pole Agnieszka Radwanska held off German qualifier Andrea Petkovic 6-4, 3-6, 6-3 and No. 15 Chinese Li Na overcame Ukrainian qualifier Kateryna Bondarenko 2-6, 7-5, 6-3.

One other Day-4 bout saw Slovakian Magdalena Rybarikova fight back to best Canadian Aleksandra Wozniak 1-6, 6-3, 6-3.

The other quarterfinals will pit Azarenka against Li and Radwanska versus Rybarikova.

This week's winner will take home $350,000.