Chinese star Li stunned at French Open
China's Li Na returns the ball to France's Kristina Mladenovic during their French tennis Open first round match at the Roland Garros stadium in Paris on May 27, 2014 - by Miguel Medina
Li, the 2011 champion, went down 7-5, 3-6, 6-1 to the 103rd-ranked blonde Frenchwoman, the Roland Garros junior champion in 2009, to suffer her first opening round defeat in Paris in eight visits.
The 2hr 06min loss on a windswept and chilly Suzanne Lenglen court saw Li undone by 37 unforced errors.
Mladenovic, who was Australian Open mixed doubles champion this year with Daniel Nestor, goes on to face Alison Riske of the United States for a place in the third round.
"It's just incredible," said Mladenovic, who was 36 in the world last Ausgust.
"I don't have the words to describe what just happened. To beat the world number two in the first round at Roland Garros, it's incredible. Without the crowd, I could not have done it."
Li's shock defeat means that both Australian Open champions have been knocked out in the first round after Stan Wawrinka's listless defeat on Monday.
Also making an early exit on Tuesday was Bulgarian men's 11th seed Grigor Dimitrov who lost 6-4, 7-5, 7-6 (7/4) to giant Croat Ivo Karlovic.
Karlovic fired 22 aces and wasn't broken by Dimitrov who won the Bucharest claycourt title this spring and was a semi-finalist at the Rome Masters.
The 35-year-old Karlovic has now equalled his best French Open performance and next faces either Daniel Brands of Germany or Austria's Andreas Haider-Maurer.
Romanian fourth seed Simona Halep reached the second round with a 6-0, 6-2 win over Russia's Alisa Kleybanova and next plays Heather Watson of Britain.
The 22-year-old Halep, the winner of seven career titles and a runner-up to Maria Sharapova at the Madrid Open claycourt event this season, raced into a 6-0, 5-0 lead before Kleybanova stopped the rot.
But the Russian, ranked 87 in the world and playing in Paris for the first time since 2010 after undergoing cancer surgery, was eventually undone by her 32 unforced errors as Halep wrapped up victory in 56 minutes.
"I was thinking at that moment at 5-0 that I can win 6-0, 6-0, but it wasn't too good. I was a little bit relaxed after that, and it was cold. I felt a little bit in my back," said Halep.
"But I stayed focused after two games lost, and then I served really well."
- Date-Krumm, 43, beaten -
Other early winners on Tuesday were Svetlana Kuznetsova, the Russian 27th seed and 2009 champion, who beat Georgia's Sofia Shapatava 6-3, 6-1 while 43-year-old Kimiko Date Krumm of Japan, a semi-finalist in 1995, lost 6-3, 0-6, 6-2 to Russian Anastasia Pavlyuchenkova, the 24th seed.
Later Tuesday, Spanish fifth seed David Ferrer, last year's runner-up to Rafael Nadal, begins his 12th Roland Garros against Dutch world 55 Igor Sijsling.
Ferrer, 32, has reached the quarter-finals or better at his last nine majors.
Britain's Andy Murray, the seventh seed, starts against Andrey Golubev of Kazakhstan.
Murray, 27, the Wimbledon champion, was a semi-finalist in 2011 but skipped the 2013 tournament through injury.
He has defeated world number 53 Golubev in both their previous meetings without dropping a set.
Former women's champion Ana Ivanovic, the Serb 11th seed, plays French world number 43 Caroline Garcia.
Ex-world number one Caroline Wozniacki, the 13th seeded Dane, tackles Belgium's Yanina Wickmayer in her first outing since her romance with golfer Rory McIlroy ended.
A quarter-finalist in 2010, the 23-year-old won her first six meetings against Wickmayer before the Belgian broke that streak in Doha this year.
Former men's world number one Lleyton Hewitt, now at 46 in the world, begins his 14th Roland Garros against unseeded Argentine Carlos Berlocq.
Hewitt, 33 and twice a quarter-finalist in Paris in 2001 and 2004, has lost 11 of his last 13 matches on clay.
His fellow Australian Bernard Tomic, now down at 80 in the world, takes on French 12th seed Richard Gasquet who is chasing his 100th career win on clay.
Gasquet has never got beyond the fourth round in Paris despite twice being a semi-finalist at Wimbledon and the US Open.
Tomic, the world number 80, has yet to win a main tour claycourt match in 2014.
He had endured a roller-coaster year with a first round, injury-hit exit at the Australian Open followed by double hip surgery and then a 28-minute defeat to Jarkko Nieminen in Miami -- the shortest completed match in history.
German 36-year-old Tommy Haas, the 16th seed, can become the oldest man since Jimmy Connors in 1991 to reach the second round if he defeats Jurgen Zopp of Estonia.
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