Paris, June 2
Defending champion Li Na needed three sets to reach the fourth round of the French Open on Saturday.
The seventh-seeded Li, who last year became the first Chinese player to win a Grand Slam singles title, held on to beat Christina McHale of the United States 3-6, 6-2, 6-1.
Li committed 44 unforced errors in the match, 20 more than her unseeded opponent.
The last woman to successfully defend her title at Roland Garros was Justine Henin, who won three straight from 2005-07.
Unseeded Varvara Lepchenko of the United States beat 2010 French Open champion Francesca Schiavone of Italy 3-6, 6-3, 8-6 in the third round at Roland Garros on Saturday.
The 63rd-ranked Lepchenko never had made it beyond the second round at any Grand Slam tournament.
But she came back to eliminate Schiavone, who was the runner-up at last yearís French Open.
Lepchenko joins Sloane Stephens, who won Friday, to give the U.S. two unseeded women in the fourth round at a major tournament for the first time since Wimbledon in 2002.
Fourth seed Petra Kvitova moved into the French Open fourth round with a 6-2 4-6 6-1 victory over Russian Nina Bratchikova on Saturday, but the Czech was forced to toil in the piercing Parisian sunshine to overcome her opponent.
Peppering the baseline with a series of snappy and accurate groundstrokes, Kvitova had looked to be on course for a smooth passage into the next round when she claimed the first set in just 28 minutes.
The Russian, however, upped her intensity in the second, forcing the match to a decider before Kvitova regained the upper hand to close it out with a double break.
Mikhail Youzhny was having such a bad day in the third round of the French Open that he felt the need to apologize, right on court during the match.
The 27th-seeded Russian scraped "SORRI" into the clay with his right foot in the middle of his 6-0, 6-2, 6-2 loss to No. 6 David Ferrer on Saturday.
Roger Federer survived another awkward French Open assignment to book a last 16 match-up with Belgiumís David Goffin, the first lucky loser in 17 years to make a Grand Slam fourth round.
Federer, the champion in Paris in 2009, overcame battling French world number 89 Nicolas Mahut 6-3, 4-6, 6-2, 7-5, being pushed to four sets for the second match in succession.
Goffin is the first lucky loser from qualifying to make the last 16 of a major since compatriot Dick Norman at Wimbledon in 1995 and the first at Roland Garros since 1978.
Top seed Novak Djokovic, bidding to become just the third man in history and first since Rod Laver in 1969 to hold all four Grand Slam titles at the same time, breezed past French qualifier Nicolas Devilder 6-1, 6-2, 6-2.
In a match-up of the highest-ranked and lowest-ranked men in the tournament, the 32-year-old Devilder, the world number 286, who missed three years of action because of an ankle injury, was swept aside.
Djokovic next faces Italian 22nd seed Andreas Seppi, who reached the last 16 of a Grand Slam at the 29th time of asking.