JOIN USQualifier Chang knocks Safina out
The Russian, dumped out of the US Open in the third round earlier this month, struggled from the start in her opening match against a player 131 places below her in the world rankings.
French Open champion Svetlana Kuznetsova followed her compatriot out of the tournament. The fifth seed was upset 7-5, 4-6, 6-3 by Germany's Andrea Petkovic, also a qualifier.
Indian tennis ace Sania Mirza crashed out with a first-round defeat in a marathon three setter against Chinese Jie Zheng.
Sania, who had to qualify for the USD two million hard-court event, went down 7-5, 2-6, 3-6 after a contest lasting more than two hours.
Sania, who has been plagued by a nagging wrist injury for more than a year now, fought hard in a see-saw opening set.
She broke her rival thrice to go 1-0 up. However, Sania ran out of steam thereafter and lost her serve four times to go down 2-6 in the second set.
The third set followed a similar script and the Indian was once again outplayed with her serve being a major let-down.
Former Tokyo winner Maria Sharapova restored some pride for Russia, however, and gave the tournament sponsors some cheer with a battling 4-6, 7-5, 6-1 win over Italy's Francesca Schiavone.
Safina's ownership of the number one spot has been a source of contention following her failure to win a maiden grand slam in 2009.
A brief holiday from tennis after her New York flop did not look to have helped the Russian, who got off to a poor start in Tokyo by losing the first set tiebreak 7-5.
The Pan Pacific title holder, given a first-round bye at the $2 million tournament, rallied to take the second with a thumping backhand, pumping her fist and screeching "Come on!"
But after seizing an early break in the deciding set, Safina's nervousness resurfaced as she tamely surrendered her serve with a double-fault at 5-4 up.
While Safina yelled at herself in Russian, the 18-year-old Chang kept her cool, completing the biggest win of her career by forcing Safina into wild forehand on her third match point.
Earlier, Ai Sugiyama's final WTA Tour appearance ended prematurely when the Japanese player retired from her first-round match with Russian Nadia Petrova while trailing 6-0, 2-1.