TOKYO — Top-ranked and defending champion Dinara Safina was knocked out in the second round of the Toray Pan Pacific Open on Monday by Taiwanese qualifier Chang Kai-chen only hours before fellow Russian Svetlana Kuznetsova was ousted in another upset.

Safina was serving for the match in the third set when she double-faulted to give up a break. Chang, ranked 132nd and playing only for the fourth time in a WTA main draw, held her own serve and then broke Safina again for a 7-6 (5), 4-6, 7-5 win to reach the third round of the $2 million tournament.
“The double fault didn’t affect me that much,” Safina said. “Whether it’s a double fault or a mistake it’s the same. It’s just the way I played at 5-4. It wasn’t the right game, I didn’t use my first serve the whole game.”
Chang converted her third match point on Safina’s forehand error after the Russian had fought back from 0-40 to 30-40.
“On match point, I was just thinking the same thing as always,” Chang said. “I wasn’t thinking ’Oh, I have match point, I’m going to win.”’
Safina’s status as the world’s top-ranked player has been under scrutiny and a third-round loss to 72nd-ranked Petra Kvitova of the Czech Republic at the U.S. Open did little to ease that. She has never won a major title — having lost finals at the French and Australian Opens this year — but has been consistent in other tournaments, winning three titles this year and four in 2008, including the Tokyo tournament.
“This is not an easy moment but that’s sport,” Safina said. “I didn’t play good in the match today. I had a lot chances in the third set and just let it go.”
Chang, who defeated Kaia Kanepi of Estonia 6-3, 6-3 in Sunday’s opening round, put Safina on the defensive from the outset, breaking the No. 1 seed twice to go up 3-0 in the first set.
Safina, who had a first-round bye, rallied to take a 6-5 lead but Chang forced and then won the tiebreaker.
Chang said the first thing that came to mind after her huge win was her parents.
“My mother doesn’t get out to watch a lot of matches but she follows the live scoring and I was thinking about what she thought when she saw today’s score,” Chang said.
Chang made her Grand Slam debut at this year’s U.S. Open, advancing to the second round where she lost to Slovakia’s Magdalena Rybarikova.
Later Monday, Germany’s Andrea Petkovic knocked out French Open champion Kuznetsova 7-5, 4-6, 6-3 to advance to the third round. Kuznetsova lost to Safina in last year’s final here.
In first-round matches Monday, Japanese veteran Ai Sugiyama, playing in her last singles draw, was forced to retire from her first-round match trailing 6-0, 2-1 to 13th-seeded Russian Nadia Petrova.
The 34-year-old Sugiyama, who announced earlier this month she was quitting the women’s circuit after 17 years, said the effects of a high temperature and stomach problems had made it impossible for her to continue playing.
No. 11 Agnieska Radwanska of Poland beat Russia’s Ekatrina Makarova 7-5, 6-3, No. 12 Samantha Stosur of Australia had a 7-5, 6-0 win over American Alexa Glatch and No. 14 Marion Bartoli of France defeated Sorana Cirstea of Romania, 6-3, 6-0.
American Venus Williams, the No. 2 seed, was to play her opening match later Monday against Russia’s Anastasia Pavlyuchenkova.