World number one Dinara Safina fell at the first hurdle in the defence of her Toray Pan Pacific Open title.
The 23-year-old Russian, who received a bye in the first round, was eliminated by qualifier Chang Kai-Chen of Chinese Taipei.
Safina, who beat Svetlana Kuznetsova in last year's final, served for the match in the third set but handed her opponent a break with a double fault.
Chang eventually won 7-6 (7/5) 4-6 7-5.
Last year's runner up, Kuznets! ova, also bowed out to a qualifier, losing her second-round match to Andrea Petkovic of Germany 7-5 4-6 6-3.
Kuznetsova, the fifth seed, struggled for rhythm on serve in the first set but seemed to have recovered when she took the second.
However, Petkovic held her nerve to win in two hours and 11 minutes.
And second seed Venus Williams also crashed out at the hands of Anastasia Pavlyuchenkova, the Russian winning 7-6 7-5.
Pavlyuchenkova served for the first set at 5-4 only to lose her serve, but took the tie-break 8-6 and raced into a 3-1 lead in the second set.
She had points for a 4-1 advantage but was pegged back to 3-3, before eventually sealing the win in the 12th game by breaking Williams to 15.
In other first-round action, Maria Sharapova survived a scare to progress at the expense of Francesca Schiavone.
The Russian, who won the event in 2005, was a set down and struggling in the second but fought back to claim a ! 4-6 7-5 6-1 win.
Local favourite Kimiko Date Krumm was ! unable t o follow up her success in Seoul as she suffered a first-round defeat at the hands of Canada's Aleksandra Wozniak, 5-7 7-6 (7/2) 6-4.
Date Krumm yesterday became the second oldest tennis player to win a singles title on the WTA Tour in the Open era when she beat Spain's Anabel Medina Garrigues in the final of the Hansol Korea Open.
In other matches, there were straight-sets wins for seeds Agnieszka Radwanska, Samantha Stosur and Marion Bartoli, while Nadia Petrova was 6-0 2-1 up when her opponent, Ai Sugiyama, retired through illness.
Ukrainian qualifier Kateryna Bondarenko advanced with a 6-3 6-1 win over Anna-Lena Groenefeld of Germany, but her older sister, Alona, lost 1-6 7-5 6-1 to Russia's Vera Dushevina.
Also advancing today were Iveta Benesova, who defeated 16th seed Virginie Razzano 6-0 in the third, Daniela Hantuchova, Zheng Jie, Shuai Peng and Magdalena Rybarikova.
