(CNN) -- Former world number one Justine Henin suffered the first blip in her comeback to competitive tennis as she crashed out in the second round of the WTA event Indian Wells in California.
Henin went out to Argentina's Gisela Dulko in her first tournament since reaching the final of the Australian Open in her grand slam comeback.
The Belgian ace had beaten Slovakian Magdalena Rybarikova in straight sets in her opening round match, but found Dulko a tougher test and slipped to a 6-2 1-6 6-4 defeat.
In another big upset, China's Li Na, who reached the last four in the Australian Open, exited to British qualifier Elena Baltacha 7-6 2-6 7-6.
It was the 65th-ranked Baltacha's first win over a top-10 player and it came after she trailed 5-1 in the deciding third-set tiebreaker.
"At 5-1, I went into the zone and I felt really strong and I just fought my heart out," said Baltacha, who still had to save two match points in the breaker.
Star attraction Henin, who put up a tremendous fight before losing to eventual champion Serena Williams in Melbourne, is returning to the WTA circuit after a 19-month layoff, and looked rusty in her loss to Dulko.
She was not the only big name in trouble as second seed Caroline Wozniacki and Russian 10th seed Maria Sharapova both struggled to advance.
Sharapova was deep in trouble at a set and 5-3 down before battling back for a 4-6 7-5 6-2 victory over compatriot Vera Dushevina.
Teenage Dane Wozniacki came from a break down in the deciding set to beat Vania King of the United States, 5-7 6-2 6-4.
"I just kept fighting for every point," Wozniacki told the official WTA Tour Web site.
The event at Indian Wells brings together the best men's and women's players in the world in a joint ATP/WTA tournament.