Alcaraz plays Nishikori in Roland Garros opener as Swiatek gets tough draw
Jannik Sinner takes on home hope Arthur Rinderknech in the world number one's first Grand Slam match since serving a three-month doping ban.
Alcaraz and Sinner have combined to win each of the last five men's Grand Slam titles and are the two chief contenders again in Paris.
Novak Djokovic, who had not won a clay-court match this season before this week, starts his latest quest for a record-setting 25th major against American Mackenzie McDonald.
Seeded sixth, Djokovic could have been drawn to meet either Alcaraz or Sinner in the quarter-finals, but Thursday's draw spared him from that prospect.
Instead, he could run into 2024 runner-up Alexander Zverev in the last eight before a potential semi-final against Sinner. Alcaraz is in the other half of the draw.
Zverev opens against US teenager Learner Tien.
Alcaraz could play Fabian Marozsan or Luca Nardi in the second round, with towering Frenchman Giovanni Mpetshi Perricard a possible third round-opponent.
The Spaniard is on course to meet 2021 runner-up Stefanos Tsitsipas or Ben Shelton in the last 16. Two-time finalist Casper Ruud is seeded to face him in the quarter-finals.
In-form Lorenzo Musetti and fourth seed Taylor Fritz are also in that half of the field.
"The confidence is really high right now. I've been playing great matches, I've got great wins in this clay season. I'm excited," Alcaraz said on Thursday.
The 22-year-old has won in Monte Carlo and Rome this season. He also reached the final in Barcelona.
Should Sinner get past the 72nd-ranked Rinderknech, he could go up against Richard Gasquet in what is the 38-year-old Frenchman's final tournament before retirement.
Alejandro Davidovich Fokina potentially lurks in the third round with Andrey Rublev and Arthur Fils possible rivals in the last 16.
Sinner could meet fifth seed Jack Draper or Alex de Minaur in the quarter-finals ahead of what would be a blockbuster clash with Djokovic.
Three-time French Open titlist Djokovic would likely have to get beyond the likes of Denis Shapovalov and Daniil Medvedev to make another deep run.
The 38-year-old Djokovic is appearing at Roland Garros for the 20th time. He has reached the quarter-finals or better at every edition of Roland Garros since 2010.
Struggling Swiatek handed tricky draw
Swiatek will need to rediscover her best form to retain the Coupe Suzanne Lenglen following a troubled past 12 months.
The Pole, who has dropped to fifth in the world, is in the same quarter as last year's finalist Jasmine Paolini, former champion Jelena Ostapenko and 2022 Wimbledon winner Elena Rybakina.
Swiatek plays Slovakian Rebecca Sramkova in the first round before a possible meeting with Britain's Emma Raducanu, the 2021 US Open winner making just her second visit to Paris.
Elina Svitolina, Belinda Bencic, Donna Vekic and Marta Kostyuk also feature alongside Swiatek in a loaded section.
"Every year is different," said Swiatek, who has not won a title since last year's French Open.
"This season has had more ups and downs than the years before but I know my game is there. I just need to figure out how to use it in the most important moments."
Four-time French Open champion Swiatek is in the same half of the draw as top seed Aryna Sabalenka, who gets under way against Kamilla Rakhimova from Russia.
Zheng Qinwen, the winner of Olympic gold on Court Philippe Chatrier last August, could await Sabalenka in the last eight.
Second-ranked Coco Gauff plays Australian Olivia Gadecki in round one and is one of four seeded Americans in the bottom quarter of the women's draw.
The 18-year-old Mirra Andreeva, attempting to become the youngest Grand Slam singles champion since compatriot Maria Sharapova in 2004, starts against Cristina Bucsa of Spain.
Naomi Osaka plays 10th seed Paula Badosa in an eye-catching first round tie, while eighth seed Zheng takes on former finalist Anastasia Pavlyuchenkova.