The Spaniard became the first man since Bjorn Borg to win three successive titles at Roland Garros.
Roger Federer reached a record eighth consecutive Grand Slam final by overcoming Nikolay Davydenko 7-5, 7-6, 7-6.
Ana Ivanovic beat the Russian 6-2, 6-1 the enter the French Open final.
Mahesh Bhupathi Radek Stepanek advanced to the semi-finals of the men's doubles at the French Open beating second seeds Jonas Bjorkman and Max Mirnyi.
World No 1 Federer's 36-set record winning streak in Grand Slam tournaments was however snapped by Tommy Robredo in the French Open quarter-finals.
Jelena Jankovic beat Czech Nicole Vaidisova while Ana Ivanovic upset 2006 runner-up Svetlana Kuznetsova.
The Australian said he saw nothing to change his opinion that the Spaniard is untouchable at Roland Garros.
Leander Paes and Meghann Shaughnessy survived a scare but Sania Mirza and Fabrice Santoro were knocked out of the mixed doubles at the French Open.
The Indo-French pair broke no sweat in defeating Vania King of the US and Frantisek Cermak of the Czech Republic 6-2 6-0 in their opening encounter at Roland Garros on Friday.
Williams surrendered her Wimbledon crown last July when she lost to the 22-year-old Serb in the third round.
Roger Federer moved into the third round of the French Open in the nick of time on Wednesday with a 6-1 6-2 7-6 defeat of wildcard Thierry Ascione.
Maria Sharapova showed there was no room for sentiment on Wednesday when she led a trio of Russian seeds into the second round of the French Open.
He was drawn in the toughest half of the draw with Nadal as well as in-form Spanish teenager Carlos Alcaraz and world number three Alexander Zverev, who could clash in the last eight.
The Spaniard plays Juan Martin del Potro of Argentina in the first round on Tuesday.
Rain played spoilsport at the French Open for the second day running when a torrential downpour stopped the action for a second time on Monday.
The Swiss needs to win in Paris to join Don Budge and Rod Laver as the only men to hold all four slams at the same time.
A pep talk from dad Richard and a timely downpour over Roland Garros rescued Serena Williams from an embarrassing first-round exit at the French Open on Sunday.
10 Interesting Glimpses from the French Open.
Images from Day 5 of the 2021 French Open, in Paris, on Thursday.
When action begins on Sunday atthe French Open, Nadal will be aiming to become the first man to win a hat-trick of French Open trophies in his first three visits to Paris.
The move is designed to favour 2002 Wimbledon champion Lleyton Hewitt and this year's runner-up Mark Philippoussis.
Eighth seed Casper Ruud rallied from a set down to beat an error-prone Marin Cilic 3-6, 6-4, 6-2, 6-2 on Friday to become the first Norwegian man to reach a Grand Slam singles final and set up a French Open title clash against 13-time champion Rafael Nadal.
IMAGES from Day 11 of the French Open at Roland Garros in Paris on Wednesday.
It will be the second time Nadal and Del Potro meet at Roland Garros. The previous match up saw the Spaniard beat Del Potro in straight sets in the opening round in 2007.
Former French Open champions Argentine Gaston Gaudio and Spaniards Carlos Moya and Albert Costa have all pulled out of Wimbledon because of injury.
No wonder Roger Federer wishes he could jump into a time machine and go back through the years to have a shot at Rod Laver or Bjorn Borg.
They set up a clash with Samantha Stosur and Paul Hanley of Australia in the semi-finals which will be played on Thursday.
The duo defeated French pair Stephanie Foretz and Nicolas Devilder to enter the second round of the mixed doubles at the French Open.
The 18-year-old is slated to meet French teenager Richard Gasquet in the third round itself.
Australia's Lleyton Hewitt is a major doubt for this month's French Open after breaking two ribs in a fall.
The Australian rejected the French Open wildcard to concentrate on his preparations for Wimbledon
While several top seeds will have their say, a look at some emerging players who could be serious contenders.
The Spaniard, sidelined by a rib injury at Indian Wells in March, hopes to build momentum in Rome before launching his campaign for a 14th French Open crown
Carlos Alcaraz announced himself in Madrid when he played with a sore ankle but still dispatched three top five players -- Rafael Nadal, Djokovic and Alexander Zverev -- en route to his second Masters title, just days after his 19th birthday.
American Williams, seeded 10th and competing in her 20th French Open, powered 22 winners and converted six of 13 break points as she picked apart the 60th-ranked Belgian in just over an hour.