Reigning French Open champion Coco Gauff recovered from a slow start to power past fellow American Taylor Townsend 6-4 6-0 as her title defence began in style.
Elsewhere in the women's draw, top-seed Aryna Sabalenka and 16th-seed Naomi Osaka also progressed.
On a baking Court Philippe-Chatrier, Gauff struggled to find her range early on and was a point away from slipping two breaks of serve behind.
But the fourth seed quickly recovered her poise to take control and move safely through to the second round.
Gauff double-faulted on set point at 5-3 in the opener but broke the Townsend serve in the next game to move ahead.
After that it was one-way traffic as she raced to victory.
"I have so many great memories on this court," said Gauff, who beat Sabalenka in the final last year.
"I was a little nervous going out, that showed a bit, but I was able to find my calm."
Top-ranked Sabalenka took advantage of the heatwave at the French Open to impose her attacking game in the first round.
Sabalenka beat 50th-ranked Jessica Bouzas Maneiro 6-4 6-2 on Philippe-Chatrier with an array of approaches to the net and volley put-aways.
"That's the most enjoyable part of the game right now - that I'm able to come to the net to play points there," Sabalenka said. "I'm super-proud that I was able to improve that part of the game."
The unusually hot conditions at Roland-Garros make net-rushing - usually better reserved for hard and grass-courts - a viable option because the court is drying out quicker and playing faster.
For a third consecutive day, the temperature in Paris was forecast to rise to at least 32 degrees.
"Let's hope that this is the perfect condition for me," Sabalenka added. "It suits my game really well."
Sabalenka has won the Australian Open and the US Open on hard courts.
Osaka turned heads with another sparkling Grand Slam fashion statement and the former world No 1 matched it with striking tennis to dismantle unseeded German Laura Siegemund 6-3 7-6 (7-3) in the first round.
Months after dazzling with a jellyfish-inspired outfit at the Australian Open, Osaka walked on to Court Suzanne Lenglen in a sequined waistcoat blouse and a black mesh floor-length train before unveiling a layered yellow-brown and gold match dress.
Siegemund, far more understated in attire, held her own once the contest began but four-time Grand Slam champion Osaka quickly took control of the opening set and closed it out with minimum fuss.
As the blazing afternoon sun made conditions more difficult for players, Osaka allowed the momentum to shift in the next set but the 16th seed saved a set point and powered back from 5-3 down to force a tie-break and prevail.
Despite her confident pre-match display, the American admitted that her choice of outfit caused her some brief on court concern.
"Athletes are in show business," Osaka said after the match. "Grand Slam walk-ons are the only time that I possibly feel like I'm an entertainer.
"I actually got a little worried, because when the sun hits the dress, it reflects a lot. So I was a little scared that the umpire was going to kick me off the court," she said. "So I (had) two back-up normal Nike dresses."
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