Li Na lost her first Grand Slam match since winning the title in Melbourne, falling to Kristina Mladenovic of France 7-5, 3-6, 6-1 on Tuesday. The loss came a day after men's Australian Open champion Stan Wawrinka was eliminated in the first round.
Li, who won the French Open in 2011 and was seeded second this year, ended up with 37 unforced errors on a cool and overcast day at Roland Garros. Mladenovic had only 25 errors.
"Nobody say if you No. 2 in the world you have to win all the matches. I mean, this is tennis," Li said. "I think doesn't matter who plays today against me; I always lose the match today because I don't think she ... put a lot of pressure [on] me. I think today just I gave it away."
In 2011, Li became the first Chinese player to win a Grand Slam title. On Tuesday, she said she wasn't feeling quite like her usual self.
"I don't think I'm doing well," Li said. "If I doing well, I believe I still can win the match if it's not my best day. But I don't think today I try a lot."
On Monday, Wawrinka lost to 41st-ranked Guillermo Garcia-Lopez of Spain 6-4, 5-7, 6-2, 6-0.
This is the first time that both Australian Open champions have lost in the first round at Roland Garros. The last Australian Open women's champion to lose in the first round in Paris was Lindsay Davenport in 2000.
Earlier, fourth-seeded Simona Halep made it through to the second round while Caroline Wozniacki and Japanese veteran Kimiko Date-Krumm didn't.
Halep won 11 straight games at the start and beat Alisa Kleybanova of Russia 6-0, 6-2.
"I was thinking at that moment, at 5-0, that I can win 6-0, 6-0, but wasn't too good," Halep said. "I was a little bit relaxed after that, and it was cold. I felt a little bit in my back.
"But I stayed focused after two games lost, and then I served really well."
The 22-year-old Romanian has never been past the second round at Roland Garros, but she entered the clay-court major as one of the favorites following a run to the quarterfinals at the Australian Open.
Playing on Court Philippe Chatrier, the main stadium at Roland Garros, Halep raced through the first set and then won the first five games of the second. But she was broken while serving for the match the first time.
Halep finished with only six unforced errors, while Kleybanova had 32.
the 13th-seeded Wozniack, about a week after her engagement to two-time major golf champion Rory McIlroy was called off, lost 7-6 (5), 4-6, 6-2 to 64th-ranked Yanina Wickmayer of Belgium.
Date-Krumm, the oldest woman in the field at 43, had an up-and-down match against 24th-seeded Anastasia Pavlyuchenkova of Russia, eventually losing 6-3, 0-6, 6-2.
Date-Krumm is the third-oldest player in French Open singles history; Martina Navratilova was 47 in 2004. She made her main-draw debut at Roland Garros in 1989 -- before more than half of this year's women's field was even born.
No. 27 Svetlana Kuznetsova, the 2009 French Open champion, also advanced, along with No. 26 Sorana Cirstea of Romania.
Li Na Stunned
Kristina Mladenovic beat 2014 Australian Open champion Li Na 7-5, 3-6, 6-1 in the first round of the French Open.