PARIS — Playing in just her 10th match of the season, Serena Williams overcame a rocky opening set at the French Open Monday to advance to the second round.

Williams, 37, was hardly at her best against Russia’s Vitalia Diatchenko, 28, who is ranked 83rd in the world and had never beaten a top-10 opponent. But she summoned her fierce fighting spirit to compensate until she found the range on her serve and groundstrokes to prevail in commanding fashion, 2-6, 6-1, 6-0.

A three-time French Open champion, Williams has scarcely been seen on court this season, limited by illness and injury, so she enters the French Open amid questions about her health and fitness. Her 2019 record, before Monday, was 7-2 after she withdrew from tournaments in Indian Wells (viral illness), Miami (left knee) and Rome (left knee).

Over the course of her 24-year pro career, Williams has started majors in rusty and ragged form before. But her pattern has been to battle her way to early-round victories while raising her level of play at each stage.

Whether she can do that here, on the French Open’s red clay, which blunts the impact of her powerful first serve, is unclear.

Amid gusty winds, her game was riddled with unforced errors in the first set, which the Russian claimed in 34 minutes.

Serving to open the second set, Williams blasted yet another ground stroke well over the baseline and howled in frustration. The outburst seemed to focus her, and she held serve. She stopped pressing and over-hitting in subsequent games. And after breaking for a 2-0 lead in the second set, she unleashed a cry of “Come on!” and rolled from there.

Seven-time French Open champion Chris Evert, an ESPN commentator who’ll provide analysis for Eurovision this fortnight, counts herself among those uncertain about Williams’s readiness for the season’s second major given how little she has competed.

“You need your body, your fitness and your legs more than anything on the red clay,” said Evert, who compiled a 382-22 career record on clay, in a telephone interview before the tournament. “Even if she does have her fitness and her health, how much preparation has she had? Is that going to affect her, too? It hasn’t been ideal.

“I think she would have liked to have played a tournament or two and gotten some more matches on red clay. So, it remains to be seen.”

Williams insisted that her lack of preparation would not be an issue. “I have enough tennis in me,” she said. “I have 30-something years’ worth of tennis, so I’ll be fine.”

Asked about Nike’s recent announcement that it would no longer financially penalize pregnant female athletes under contract, Williams, Nike’s highest-profile female endorser, whose contract terms weren’t affected by her pregnancy, said: “They said they want to make a change. They want to support women that want to have families and that want to be moms. I’m glad that statement was made, and I know that going forward, they’re doing better. That’s what it’s about. It’s about learning from mistakes and doing better.”

She also made a strong fashion statement in her return to Roland Garros, one year after a French tennis official took issue with the black catsuit she wore here last year.

A 23-time Grand Slam champion, Williams strode onto Philippe Chatrier Court in a billowy, black and white striped outfit that consisted of an asymmetrical skirt and long-sleeved blousy jacket that fluttered in the late afternoon breeze.

She had previewed the outfit via an Instagram post Sunday, alongside its creator, fashion designer Virgil Abloh, founder of the Milan-based label Off-White and the men’s designer at Louis Vuitton’s menswear line. It is her second Nike tennis-wear collaboration with Abloh, who designed the one-shoulder dress with flouncy, ballet-inspired tulle skirt that Williams wore at the 2018 U.S. Open.

After a brief warm-up with Diatchenko, Williams unzipped the jacket to reveal a fitted top-that repeated the skirt’s striped pattern. Williams explained that there are four words in French woven into the fabric of the outfit: “Champion,” “Queen,” “Mother” and “Goddess.”

Williams was criticized by one French tennis official, who said after the fact that her catsuit had “gone too far” and suggested that it showed a lack of respect for the game.

Williams explained that she wore the outfit — a compression suit — largely as a medical precaution to help guard against a recurrence of blood clots that endangered her life during the birth of her first child, daughter Alexis Olympia, on Sept. 1, 2017, roughly nine months prior.

Read more from The Post: