TOKYO --  Venus Williams rallied from a set down to defeat Simona Halep of Romania 4-6, 7-5, 6-3 Wednesday and reach the quarterfinals of the Pan Pacific Open.

Williams, making her first appearance in the Tokyo tournament since 2009, broke serve to lead 5-3 in the third set at Ariake Colosseum. She then won with a crosscourt forehand that No. 13-seeded Halep hit into the net.

"It was a very tough match," Williams said. "She played very well. I don't know how I was able to win the match. I just wanted to stay in Japan longer."

Williams, who ousted top-seeded Victoria Azarenka on Tuesday, will face Canada's Eugenie Bouchard in the quarterfinals.

Bouchard upset sixth-seeded Jelena Jankovic of Serbia 7-5, 6-2.

Making her debut in the Tokyo tournament, Bouchard broke Jankovic to go up 5-2 in the second set and then held serve to win.

Jankovic had a 5-4 lead in the first set but Bouchard won the last three games after a talk with her coach.

"I felt like I wasn't playing my best in the first set," Bouchard said. "But I stayed with her and started to get a lot more aggressive near the end of the first set and that was the turning point."

The 46th-ranked Bouchard won last year's junior Wimbledon title.

"That gave me a lot of confidence to play in the pros," Bouchard said. "Playing week in, week out against the top players has made me a better player."

In other third-round matches, fourth-seeded Caroline Wozniacki defeated Magdalena Rybarikova 6-1, 6-1, and second-seeded Agnieszka Radwanska beat Dominika Cibulkova 6-3, 6-4.

Fifth-seeded Angelique Kerber of Germany defeated No. 11-seeded Ana Ivanovic of Serbia, 6-4, 6-2, and Lucie Safarova of the Czech Republic beat No. 12-seeded Samantha Stosur of Australia, 6-4, 6-4.

Copyright 2013 by The Associated Press