Tokyo, Japan (My Sportsbook) - Top-seeded and defending champion Dinara Safina, second-seeded Venus Williams and French Open titlist Svetlana Kuznetsova were a trio of second-round upset victims at the hands of qualifiers Monday at the $2 million Pan Pacific Open. Unseeded Russian star Maria Sharapova was among Day 2's opening-round winners.

The Australian Open and French Open runner-up Safina fell to 18-year-old qualifier Kai-Chen Chang of Taipei 7-6 (7-5), 4-6, 7-5 on the hardcourts at Ariake Colosseum. Safina beat Kuznetsova in last year's all-Russian finale here.

The 132nd-ranked Chang, who stunned Safina in 2 hours, 44 minutes, made her 2009 WTA Tour main draw debut at the U.S. Open earlier this month, reaching the second round.

The Wimbledon runner-up Williams was ousted by Russian qualifier Anastasia Pavlyuchenkova 7-6 (8-6), 7-5 in just under two hours. The Russian tallied four service breaks, compared to three for the loser Williams on Day 2.

A fifth-seeded Kuznetsova, meanwhile, succumbed to German qualifier Andrea Petkovic 7-5, 4-6, 6-3. Kuznetsova bested Safina in an all-Russian French Open final back in June.

The former top-ranked and 2005 Pan Pacific titlist Sharapova overcame Italian Francesca Schiavone 4-6, 7-5, 6-1.

Last week's surprise Seoul champion, 39-year-old Japanese wild card Kimiko Date Krumm, came up an opening-round loser at the hands of Canadian Aleksandra Wozniak, 5-7, 7-6 (7-2), 6-4.

Four seeded women notched first-round wins on Monday, as No. 11 Pole Agnieszka Radwanska handled Russian Ekaterina Makarova 7-5, 6-3; No. 12 Aussie Samantha Stosur stopped American qualifier Alexa Glatch 7-5, 6-0; No. 13 Russian Nadia Petrova got past ill Japanese wild card Ai Sugiyama 6-0, 2-1, retired; and No. 14 Frenchwoman Marion Bartoli blitzed Romanian Sorana Cirstea 6-3, 6-0.

A first-round upset came when Czech Iveta Benesova bounced 16th-seeded Frenchwoman Virginie Razzano 3-6, 7-6 (7-5), 6-0.

Additional opening-round wins came for Slovakians Daniela Hantuchova and Magdalena Rybarikova, Chinese Zheng Jie and Peng Shuai, Russian Vera Dushevina, and Ukrainian qualifier Kateryna Bondarenko, who will face third- seeded Olympic gold medalist Elena Dementieva in the round of 32 here.

This week's winner will take home $350,000.