Three more seeded players failed to advance to the second round on Tuesday, including 10th-seeded Grigor Dimitrov who faltered at the first hurdle for the second straight year in Paris.
Two of the seeded women exited: No. 6 Eugenie Bouchard, the highest-seeded player to lose so far, and No. 25 Jelena Jankovic.
That's it for today. Bonsoir.
One little laughing fit after a ball took an awkward hop did nothing to slow Serena Williams.
The top-ranked Williams needed less than an hour to defeat French Open qualifier Andrea Hlavackova of the Czech Republic 6-2 6-3.
That improved Williams to 58-1 in first-round matches at majors.
The 33-year-old American is going for her 20th Grand Slam singles title. Only two women have won more — Margaret Smith Court (24) and Steffi Graf (22).
Who says Americans can't win on the red clay of Paris?
Jack Sock, a 22-year-old who was born in Nebraska and is now based in Florida, has pulled off a French Open upset, eliminating 10th-seeded Grigor Dimitrov of Bulgaria.
Pounding serves at up to 136 mph (220 kph), whipping big forehands and winning the point on 19 of 25 trips to the net, the 37th-ranked Sock beat Dimitrov 7-6 (7), 6-2, 6-3 in less than two hours.
Sock has never been past the third round at a Grand Slam tournament.
Dimitrov was a semifinalist at Wimbledon last year.
For just a moment, brief as can be, Novak Djokovic was in a bit of a tight spot in the first round of the French Open.
Djokovic found himself two points from dropping the second set when his opponent, 87th-ranked Jarkko Nieminen of Finland, was serving at 5-3, 30-love.
But Djokovic dug out of that hole, grabbed 22 of 29 points, and wound up stretching his winning streak to 23 matches with a 6-2, 7-5, 6-2 victory.
The top-ranked Serb is trying to complete a career Grand Slam by winning his first title at Roland Garros.
Perhaps with a post-tournament victory speech in mind, Djokovic has been working with a tutor to improve his French. He conducted his post-match, on-court interview in the local language — much to the crowd's delight.
"I'm very excited to speak French," Djokovic told the fans. "Hopefully my teacher will say that I was good."
The losses keep mounting for Eugenie Bouchard, who was so good last year and is having so much trouble nowadays.
At No. 6, Bouchard is the highest-seeded player to exit the French Open so far, beaten 6-4, 6-4 in the first round by 44th-ranked Kristina Mladenovic of France on Court Suzanne Lenglen.
Bouchard has now lost eight of her past nine matches.
Last season, the Canadian appeared to be establishing herself as one of tennis' next big stars, reaching three consecutive Grand Slam semifinals, including at the French Open. She made it all the way to the final at Wimbledon.
Toni Nadal, Rafael's uncle and coach, says the nine-time French Open champion's strokes are just fine.
"He is hitting the ball good enough. No worse than years ago," Toni told The Associated Press.
The problem this season — Rafael came to Paris 17-5 on red clay, his most losses on the surface in a single year since 2003 — is self-belief.
"Confidence is the most important thing," Toni said. "You can hit a good ball, but you need to win matches to have confidence."
Fourteen winners, three aces and two breaks: 6-2 in 35 minutes.
Top-ranked Novak Djokovic just won the opening set of his first-round match against Jarkko Nieminen on centre court at the French Open.
Rafael Nadal didn't really get much of a test in the first round.
The nine-time French Open champion began his bid for title No. 10 at the clay-court Grand Slam tournament with a 6-3, 6-3, 6-4 victory over Quentin Halys, an 18-year-old wild-card entry from France who is ranked 296th and had never played a match at a major tournament.
Nadal has won 67 of his 68 career matches at Roland Garros, including the last 36 in a row.
Now this was one awkward post-match handshake.
Jerzy Janowicz aggressively grabbed opponent Maxime Hamou's hand when they met at the net after the Pole's 6-7 (4), 6-3, 6-4, 6-4 win at the French Open.
Then each player pointed at the other, exchanging glares.
And Janowicz, a Wimbledon semifinalist in 2013, offered an etiquette lesson, too.
He was steamed that Hamou had failed to offer an apology after hitting a return right at Janowicz even though a serve had been called out.
"I said, 'You're supposed to say sorry,'" Janowicz recounted later.
He said Hamou didn't reply.
For his part, Hamou denied he aimed at Janowicz on purpose, noting: "He had plenty of time to avoid it."
Here's a link to a video of their handshake:
It was a tricky test, but Caroline Wozniacki passed it smoothly.
The former top-ranked player from Denmark stopped Karin Knapp's good run on clay this season with a 6-3, 6-0 win to reach the second round of the French Open.
Knapp arrived in Paris on the back of her second career title at the Nuremberg Open last week and with an 8-2 record on clay. But she was no match for the fifth-seeded Wozniacki, who made it to the quarterfinals at Roland Garros five years ago.
Wozniacki saved the only break point she faced in the first set and limited her mistakes to nine unforced errors.
Petra Kvitova has made it through to the second round of the French Open after a tougher-than-expected struggle.
The two-time Wimbledon champion edged 80th-ranked Marina Erakovic of New Zealand 6-4, 3-6, 6-4.
Surprisingly, two-time Wimbledon champion Petra Kvitova has been pushed into a third set on Court Philippe Chatrier.
The fourth-seeded Czech was broken to drop the second set 6-3 after taking the opener 6-4 against Marina Erakovic of New Zealand, who is ranked 80th and never has made it past the third round at any Grand Slam tournament.
They've played four times previously, with Kvitova going 4-0.
Over on Court 2, reigning U.S. Open champion Marin Cilic eased into the second round by beating Robin Haase 6-2, 6-4, 6-2.
It's Cilic's first Grand Slam match since winning his title in New York in September. He missed the Australian Open in January because of an injured shoulder.
A final cross-court forehand winner at the net and David Ferrer is through to the second round at the French Open.
Runner-up at Roland Garros two years ago, the Spaniard recorded his 300th career match-win on his favourite surface with a 6-1, 6-3, 6-1 win over 94th-ranked Lukas Lacko on Court Suzanne Lenglen.
In 13 straight appearances at the clay-court major, the seventh-seeded Ferrer has always won his opening match.
Along with Novak Djokovic and Rafael Nadal, there is a third Grand Slam champion in action in the men's draw at Roland Garros on Tuesday.
Marin Cilic, who won the U.S. Open last year, is up against 80th-ranked Robin Haase on Court 2. Things are going well so far for the ninth-seeded Croat, who has converted both break points and served out the opening set 6-2.
Cilic is playing in his first major of the year after missing the Australian Open because of a shoulder injury.
There is no Royal Box at Roland Garros, but the "King of Clay" will be on centre court on Day 3 with nine-time champion Rafael Nadal in action.
Top-ranked Novak Djokovic and Serena Williams will also be starting their campaigns in Paris.
Although he won't play before mid-afternoon, The Associated Press spotted Djokovic in an official car on his way to the stadium, shades on, at about 9:30 a.m. Up against Jarkko Nieminen, the Serb is carrying a 22-match winning streak into the tournament where he chases the only Grand Slam title missing from his collection.
Nadal takes on teenager Quentin Halys, who has never played a match at a major tournament, while Serena will try to do better than her older sister Venus, who lost in the first round on Monday.
Bidding for a third title at the French Open, Serena faces qualifier Andrea Hlavackova.
And what about the weather? It should be cloudy but dry most of the day, with a high of 68 degrees F (20 degrees C).