Iga Swiatek celebrated her 20th birthday in style on Monday, overcoming Kaja Juvan in straight sets to get her French Open title defence off to a strong start.

Swiatek clinched her maiden grand slam – and first senior career title – at Roland Garros in 2020, and the Pole was in supreme form as she confidently saw off close friend Juvan 6-0 7-5.

A champion in Rome in the lead-up to Roland Garros, Swiatek made it 20 game wins in a row – dating back to her Internazionali d'Italia semi-final against Coco Gauff – until Juvan held her own in the second game of the second set.

Swiatek saved two break points at 5-5 before wrapping up the win.

"It's never easy to play against your best friend," Swiatek said after the match. "I have some experience because I played with Kaja for a few times. I've played with my other friends on junior level.

"You just try to block this friendship for two hours, just focus on the game.

"I think I'm doing that pretty well. It's nice to have that skill. So I was just trying to treat Kaja as any other girl, as any other opponent, because in sports when we are on court you can't have thoughts that are you going to make your game softer."

ANGUISH FOR ANDREESCU 

There was no such route through for Bianca Andreescu, the sixth seed coming unstuck against world number 85 Tamara Zidansek.

Andreescu's stint at this year's French Open lasted three hours and 20 minutes, but the world number four could not find a way through and duly became the biggest women's casualty of the first round so far.

The 2019 US Open champion headed into the tournament on the back of pulling out of a quarter-final at the Internationaux de Strasbourg due to an abdominal injury and was playing in only her third tour-level match on clay. She won the opening set on a tie-break, yet it was Zidansek who prevailed 6-7 (1-7) 7-6 (7-2) 9-7 to claim her first win over a top-10 opponent.

Kiki Bertens was another seed to drop out, the number 16 going down 6-1 3-6 6-4 to Polona Hercog.

KENIN BATTLES ON

World number five Sofia Kenin saw off a tough challenger in the form of 2017 Roland Garros champion Jelena Ostapenko.

"I knew it was gonna be a tough match, she's a great player," Kenin said, after a 6-4 4-6 6-3 victory. "I knew I needed to play my best tennis in order to win."

Kenin, 22, came from a break down twice to take the opening set, and though Ostapenko hit back, American Kenin held her nerve in the decider, setting up a second-round tie with compatriot Hailey Baptiste.

"I'm a feisty kid, and I have to fight in order to win," added Kenin, who lost to Swiatek in last year's final but has struggled for results in 2021. "I've got a little bit of feistiness in me and that helps me in these types of matches."

Naomi Osaka's decision to boycott mandatory media interviews at the French Open has left tennis legend Billie Jean King "torn".

Osaka revealed in the build-up to the second grand slam of the year that she would not partake in media duties, stating that "people have no regard for athletes' mental health" during news conferences.

The WTA – organisers of the women's tour – encouraged the Japanese superstar to reach out for support with her mental well-being but stressed she had a "responsibility" to her sport to honour contractual commitments.

The 23-year-old conducted an on-court interview after beating Patricia Maria Tig on Sunday but did not appear at the allotted time for her post-match media conference and was hit with a $15,000 by tournament organisers, who threatened further sanctions, including a possible suspension.

King, a 12-time grand slam singles champion, took to Twitter to outline her stance on what is proving to be a contentious issue.

"I fully admire and respect what Naomi is doing with her platform, so I am a little torn as I try to learn from both sides of the situation," wrote King, a co-founder of the WTA.

"While it's important that everyone has the right to speak their truth, I have always believed that as professional athletes we have a responsibility to make ourselves available to the media.

"In our day, without the press, nobody would have known who we are or what we thought. There is no question they helped build and grow our sport to what it is today.

"I acknowledge things are very different now with social media and everyone having an immediate ability to speak their truth.

"The media still play an important role in telling our story. There is no question that the media needs to respect certain boundaries.

"But at the end of the day it is important that we respect each other and we are in this together."

Osaka plays Ana Bogdan in round two on Wednesday.

Naomi Osaka fended off Patricia Maria Tig at the French Open on Sunday, but the world number two admits she has plenty of room for improvement on clay.

Osaka has been at the centre of attention in the build-up to the tournament, with the 23-year-old refusing to attend mandatory news conferences and suggesting they were not beneficial to her mental health.

The second seed stood by her decision following a straight-sets win over Romanian Tig and was subsequently handed a $15,000 fine and warned repeat offences could see her thrown out of the competition.

However, Osaka did speak in an on-court interview after her 6-4 7-6 (7-4) victory on Court Philippe-Chatrier– just her second win of the season on clay.

"I'd say it’s a work on progress," four-time grand slam winner Osaka said when asked about her clay-court game.

"Hopefully, the more I play the better it'll get. I'm really glad that I won, it's a very beautiful court. I've only played two matches here – one before the roof [was installed] and one right now. Hopefully I'll keep it going."

Next up for reigning US and Australian Open champion Osaka is Ana Bogdan, who defeated Elisabetta Cocciaretto 6-1 6-3.

ANOTHER FRENCH OPEN DUCK FOR KERBER

While Osaka took a place in round two, former world number one Angelique Kerber had no such luck as she came unstuck in the first round at Roland Garros for a third year running.

Now ranked at 27th in the world by the WTA, Kerber lost 6-2 6-4 to qualifier Anhelina Kalinina.

The French Open title has so far eluded Kerber, who has won every other grand slam, and the 33-year-old German has not won a match in Paris since 2018, when she reached the quarter-finals, having also made the last eight in 2012.

Indeed, the 33-year-old's run to the quarters in 2018 was the only time in her last six appearances at Roland Garros that she has progressed beyond the first round.

"She started well and had nothing to lose, while it took me too long to get into the contest," Kerber said. "I will try to learn from the match now because I played good the last few weeks and I had good matches."

SABALENKA AND KVITOVA BATTLE THROUGH

Aryna Sabalenka was the other top seed in action on Sunday, though she was made to work for a 6-4 6-3 defeat of Ana Konjuh.

The third seed, who is in the hunt for a first grand slam title having already won the Madrid Open this month, made a sluggish start and two breaks of serve had her 4-2 down to world number 144 Konjuh.

But Sabalenka rallied herself and a streak of four straight games handed her the set, and a further three successive breaks to start the second put her in command.

Konjuh managed to save the first match point, only for the Croatian qualifier to hit the net as Sabalenka progressed at the second time of asking.

Petra Kvitova, the 11th seed, needed three sets to overcome Greet Minnen 6-7 (3-7) 7-6 (7-5) 6-1, and had to save a match point in the process.

Two-time Wimbledon champion Kvitova was on the edge of a shock exit at 6-5 and a break down in the second set, but a backhand winner rescued her from the brink and forced another tie-break, which the Czech won before carrying the momentum into the decider.

"I would say that from my side it wasn't really good from the beginning," said Kvitova, a semi-finalist at Roland Garros last year.

"I was struggling, I was missing a lot, I was double-faulting a lot.

"I didn't really feel myself that well. I was pretty tight, it was really tough. I mean, I was fighting not only with her but with myself as well. I'm glad that in the end I beat myself as well and beat her, so that counts."

Kvitova will next face Elena Vesnina, who beat lucky loser Olga Govortsova 6-1 6-0 to seal a first singles win since she became a mother in 2018 and took a two-year break from tennis.

Naomi Osaka has been fined and threatened with possible expulsion from the French Open after choosing not to take part in mandatory media interviews at the tournament.

Osaka declared her intentions in the build-up to the second grand slam of the year, stating that "people have no regard for athletes' mental health" during news conferences.

The WTA – organisers of the women's tour – encouraged the Japanese superstar to reach out for support with her mental well-being but stressed she had a "responsibility" to her sport to honour contractual commitments.

The 23-year-old conducted an on-court interview after beating Patricia Maria Tig on Sunday but did not appear at the allotted time for her post-match media conference.

Tournament organisers have fined Osaka $15,000 for breaching their code of conduct and warned she could be defaulted from the French Open – and face possible suspensions from other majors – should she continue a media blackout.

Osaka, holder of the US Open and Australian Open titles, has previously said any such fines should go towards a mental health charity.

A statement on the French Open's official website read: "Naomi Osaka announced last Wednesday on social media that she would not participate in the mandatory media interviews at Roland Garros 2021.

"Following this announcement, the Roland Garros teams asked her to reconsider her position and tried unsuccessfully to speak with her to check on her well-being, understand the specifics of her issue and what might be done to address it on site.

"Following the lack of engagement by Naomi Osaka, the Australian Open, Roland Garros, Wimbledon and the US Open jointly wrote to her to check on her well-being and offer support, underline their commitment to all athletes' well-being and suggest dialogue on the issues. She was also reminded of her obligations, the consequences of not meeting them and that rules should equally apply to all players.

"Naomi Osaka today chose not to honour her contractual media obligations. The Roland Garros referee has therefore issued her a $15,000 fine, in keeping with article III H. of the code of conduct."

The statement went on to say: "We have advised Naomi Osaka that should she continue to ignore her media obligations during the tournament, she would be exposing herself to possible further code of conduct infringement consequences.

"As might be expected, repeat violations attract tougher sanctions including default from the tournament and the trigger of a major offence investigation that could lead to more substantial fines and future grand slam suspensions.

"We want to underline that rules are in place to ensure all players are treated exactly the same, no matter their stature, beliefs or achievement.

"As a sport there is nothing more important than ensuring no player has an unfair advantage over another, which unfortunately is the case in this situation if one player refuses to dedicate time to participate in media commitments while the others all honour their commitments."

The statement was co-signed by organisers from all four grand slams.