Chinese sixth seed Li Na, the 2011 champion, cruised into the French Open second round on Monday with a 6-3, 6-4 win over Anabel Medina Garrigues.

The 31-year-old Li, who will face Bethanie Mattek-Sands of the US for a place in the last 32, had lost all three of her previous career meetings on clay against Garrigues.

Li's form on the surface has been up and down in 2013, a runner-up finish to Maria Sharapova in Stuttgart followed by a first-round loss in Madrid and a third-round exit in Rome.

Under the watchful gaze of coach Carlos Rodriguez, the man who engineered Justine Henin's successes in Paris, Li was quickly 5-1 up in the first set.

But the experienced Garrigues, playing in her 38th consecutive Grand Slam main draw, rallied late on with two games before the Chinese star settled to take the opener after 48 minutes.

In a roller coaster of a tie, Garrigues was 2-0 up in the second set before Li hit back for 4-3.

The Spanish 30-year-old clung on for 4-4 before Li broke for a 5-4 advantage and then sealed the win when her opponent went long with a service return.

In all, the match featured 10 breaks of serve.

In men's event, Rafael Nadal's bid for an unprecedented eighth French Open title was given a huge scare by unheralded German Daniel Brands before the Spanish superstar prevailed 4-6, 7-6 (7/4), 6-4, 6-3.

Nadal was clearly rattled and a double fault gave the German a break for 5-4 in the opener and the set was wrapped up with a down-the-line winner.

It was only the 15th set Nadal had lost in his Roland Garros career.

Brands continued his fearless assault in the second set, taking a 3/0 lead in the tiebreaker which could have been 4/2 had he not blundered with a simple backhand volley.

That miss proved the turning point and Nadal didn't give him another chance as he took the breaker to level the tie at a set apiece.

The Spaniard was quickly 2-0 ahead in the third set, saved a break point in the eighth before a brutal forehand winner gave him a two sets to one lead.

A break in the opening game of the fourth set gave Nadal the edge he needed and the tie was his when Brands went wide with a weary forehand.

Women's fourth seed Agnieszka Radwanska also advanced to the second round.

The Pole, who has never got beyond the last 16 in Paris, breezed past Israel's Shahar Peer 6-1, 6-1 and will face America's Mallory Burdette in the next round.

She is scheduled to face younger sister Urszula, who knocked out Venus Williams on Sunday, in the third round.

The Pole, last year's Wimbledon runner-up, came into Paris nursing a shoulder injury which forced her to withdraw from Brussels last week and contributed to second-round exits in Madrid and Rome.

But Radwanska, with her hair now dyed blonde just like her sister, said she is fit enough to last the distance at Roland Garros.