Ivanovic, seeded second in Tokyo, has sagged since winning the French Open and taking over the No. 1 ranking in the world. Since then she is 4-4, including Thursday's 6-1, 1-6, 6-2 loss to Nadia Petrova.

Discounting the second set when she didn't face a break point, Ivanovic only got her first serve in about half the time and Petrova took advantage with five service breaks.

Top-seeded Jelena Jankovic and third-seeded Elena Dementieva played more to form, each needing just more than an hour to advance out of the tournament's second round. Jankovic beat Flavia Pennetta 6-2, 6-1 in 61 minutes while Dementieva stopped Alize Cornet 6-0, 6-3 in 69 minutes.

Fifth-seeded Svetlana Kuznetsova also romped Thursday, winning 6-1, 6-1 -- in 46 minutes -- over Ayumi Morita and No. 6-seeded Agnieszka Radwanska was a solid 6-2, 6-3 winner over Marion Bartoli.

In a match involving non-seeded players, qualifier Katarina Srebotnik was a straight-set victor over Francesca Schiavone 6-4, 6-3.