Jelena Jankovic’s half-season to forget took another turn for the worse Wednesday as she was bounced in the third round of the Tokyo Pan Pacific Open by Kaia Kanepi.

After a 31-10 start to the season, Jankovic has gone just 5-7. It’s Kanepi’s second consecutive high-profile defeat of Jankovic, having eliminated her in the third round of the US Open last month. She’ll face Francesca Schiavone in the quarterfinals.

Losing in the third round after making the final a year ago means Jankovic will lose 425 points in next week’s WTA rankings, and fall to No. 8 from No. 6, surpassed by Samantha Stosur and Schiavone.

Schiavone, who lost in the first round here a year ago, ended the Cinderella run of Kimiko Date Krumm with a 6-3, 6-3 victory on Wednesday. The French Open champion has a chance to climb as high as fifth if she is to win the tournament after falling in the first round a year ago.

Other than Jankvoic, the higher seeds prevailed in the rest of Wednesday’s third-round action, as did the lone American in the field. Qualifier Coco Vandeweghe overpowered German’s Julia Goerges two days after Goerges upset Samantha Stosur. Vandeweghe will take on eighth-seeded Victoria Azarenka in the quarterfinals.

  Top-seeded Caroline Wozniacki defeated Anastasia Pavlyuchenkova to reach the quarterfinals, where she’ll battle Poland’s Agnieszka Radwanska, a 6-3, 6-3 winner over Andrea Petkovic.

  On the other side of the bracket, there’ll be an all-Russian quarterfinal between second-seeded Vera Zvonareva and seventh-seeded Elena Dementieva. Both advanced with easy straight set victories. By reaching the quarterfinals, Zvonareva has closed the gap on Venus Williams to just 21 points in the WTA Rankings.

  If she reaches the semifinals, she’ll take over the No. 3 ranking for the first time in her career. Williams lost in her first match here a year ago, and opted not to play in the tournament in 2010. There’s even a chance Zvonareva could leave Tokyo ranked No. 2 in the world.

If she were to win the title while Wozniacki loses in the quarterfinals or semifinals, Zvonareva would pass her for the second spot in the world.