Eighth seed Ai Sugiyama was easily beaten in the second round by fellow Japanese player Saori Obata.
Obata took the first set 6-4, and opened up a 4-0 lead in the second set, before the eighth seed started mounted a fightback.
Sugiyama managed to break back to 4-2, but Obata kept her nerve and eventually closed out the second set 6-4.
Obata's reward is a third-round match-up with Tzipora Obziler or 29th seed Nathalie Dechy.
There was no such trouble for last year's losing finalist Venus Williams, who easily beat Russian Vera Douchevina.
The third seed showed no signs of the ankle injury she picked up in the last round as she raced to a 6-4 6-2 win in 56 minutes.
Afterwards she said that she would keep her schedule light in order to avoid further injuries.
"You can't go gung-ho and get out there and play for five hours because you'll get five more injuries," she said.
"I eased into it. Even now, I'm trying not to play too many events and I'm watching how much I train.
"On court, I'm clear about my technique and can bring down the errors when I need to."
Her fellow American Chanda Rubin beat Denisa Chladkova 6-2 6-4.
The ninth seed will next play Elena Likhovtseva, who beat 18th seed Francesca Schiavone 6-2 6-2.
Another seed on her way out was 27th ranked Amanda Coetzer, who went down 7-5 6-3 to Dinara Safina, Marat Safin's younger sister.
One seed who had no trouble progressing was sixth ranked Anastasia Myskina, who beat Emmanuelle Gagliardi 6-2 6-4.