TORONTO — Venus Williams' tuneup for the U.S. Open hit a surprising roadblock Tuesday with a 1-6, 7-5, 6-4 loss to Ukraine's Kateryna Bondarenko in the second round of the Rogers Cup.

Williams, seeded third, lost to an opponent ranked No. 64. Williams was playing at this tournament for the first time since 1997 when she was 17. She has lost all three of her matches at the Rogers Cup.

"I was definitely expecting to play well and to go very far in the tournament," Williams said. "I've got a lot of fans here, so it's disappointing."

Bondarenko will play Agnes Szavay of Hungary or Agnieska Radwanska of Poland in the third round.

"I was playing really good," Bondarenko said. "The first set, I didn't know what to do with her power. The rest of the game, I just tried to keep the ball in play."

Williams tried to find some consolation in the defeat, with the U.S. Open starting Aug. 31.

"I have to take it as a positive," she said. "Now it'll give me a chance to rest. It's been a really busy summer for me."

Williams controlled the first set but couldn't shake Bondarenko, who chased down shot after shot in stifling Rexall Centre. Bondarenko broke Williams three times in the second set and once more in the third. She won 20 of 28 service points in the deciding set.

"She played well," Williams said. "She really started playing consistently. Unfortunately I made too many errors. I would have liked to play a cleaner match."

Bondarenko initially said it was "just another match," but quickly changed her mind.

"It's big because it was against Venus," she said, adding she now feels she can beat anyone if she can defeat an opponent of this stature.

Kim Clijsters cruised past Elena Baltacha 6-3, 6-4, advancing in her second tournament since taking more than two years off to have a child.

Ana Ivanovic rallied past Magdalena Rybarikova of Slovakia for a 2-6, 6-3, 6-2 triumph. Ivanovic, seeking her first WTA Tour title of the season, had seven double-faults against Rybarikova, ranked No. 47.

"I was trying to play a little too safe, I think," said Ivanovic, who will meet Lucie Safarova of the Czech Republic in the second round. "She's a good player, and she was playing really aggressive and dominant."

Safarova advanced with a 6-4, 7-6 (3) win over Kaia Kanepi.

Also, Dominika Cibulkova beat Sara Errani 6-4, 6-2, Shahar Peer of Israel downed Monica Niculescu of Romania 6-4, 4-6, 7-6 (4) in just under three hours; Virginie Razzano of France defeated Ekaterina Makarova of Russia 6-7 (3), 6-0, 6-2; Zheng Jie of China downed Elena Vesnina of Russia 6-3, 6-2; Alla Kudryavtseva of Russia beat Julie Coin of France 6-2, 1-6, 7-6 (8); Yaroslava Shvedova of Kazakhstan earned a 7-6 (1), 7-6 (4) win over Daniela Hantuchova of Slovakia.