Tournament favourite Novak Djokovic beat Finnish veteran Jarkko Nieminen 6-2, 7-5, 6-2 on Tuesday, kicking off his quest for a first ever Paris trophy to add to his eight other Grand Slams.
He wobbled in the second set, having to pull out some of his sliding, rubber-limbed best to avoid going 5-1 down against the 33-year-old who had one previous victory against the Serb.
Once he saved a break point with a carved volley after a long exchange he reeled in his opponent who gave full value in an entertaining first-round encounter. But with even his bright ochre shirt matching the Paris clay, the World No 1 looked comfortable on court Philippe Chatrier, breaking the Nieminen serve in the very first game of the match and rarely having to move into top gear.
87th-ranked Nieminen pleased the crowd when he saved two match points in the seventh game of the third set, but Djokovic made sure in the next game to extend his winning streak to 23.
By adding the French to his string of Slams in Melbourne, Wimbledon and Flushing Meadow, Djokovic, who turned 28 last week, would join an elite group of just eight men in history to have won all four tournaments.
Djokovic, who will face either Gilles Muller or Paolo Lorenzi in round two, is in line for a quarter-final blockbuster against nine-time champion Rafael Nadal.
Twice former champion Serena Williams made a low-key start to her French Open campaign with a 6-2, 6-3 victory over Czech qualifier Andrea Hlavackova.
The World No 1, eyeing a 20th grand slam singles title, raced into a 3-0 lead but was given a decent workout after that by a player she beat 6-0, 6-0 in their only previous meeting, three years ago at the US Open.
Hlavackova broke the mighty Williams serve in the fifth game, but the first set was otherwise mostly one way traffic as the American unloaded some heavy groundstrokes under grey skies on a cool day on court Philippe Chatrier.
Williams, who has already bagged the Australian Open title this year, last won the title in Paris in 2013 and has reached the quarter finals or better eight times, although she crashed out in round two last year to Spaniard Garbine Muguruza.
Arch rival and defending champion Maria Sharapova, also looking for a third Paris win, awaits at the other end of the draw for a potential final.
Czech fourth seed Petra Kvitova dug deep to reach the second round of the French Open as she laboured to a 6-4 3-6 6-4 victory against New Zealand's Marina Erakovic.
The double Wimbledon champion looked nothing like the player who defeated world number one Serena Williams en route to the Madrid Open claycourt title earlier this month as she put in a shaky performance on court Philippe Chatrier.
"I knew it would be difficult, I always struggle at the beginning of tournaments," Kvitova, who will next take on either France's Pauline Parmentier or Silvia Soler-Espinosa of Spain.
Seventh seed David Ferrer, runner-up to Nadal two years ago, needed little more than an hour to thrash Slovakian Lukas Lacko 6-1, 6-3, 6-1, about the same time US Open champion Marin Cilic required to hammer Dutchman Robin Haase 6-2, 6-4, 6-2.
The 2013 runner-up racked up his 37th career win at Roland Garros, second only among Spaniards, to the 66 Nadal has earned in a decade of unprecedented dominance at the claycourt slam.
Ferrer lost his opening service game but was untroubled thereafter as he swept past the world number 94.
US Open champion Marin Cilic says wins are the only real recovery medicine from the shoulder injury that delayed the start of his 2015 season.
"I feel the game is there. I'm playing all right in training. It's just a matter to put it in the matches," the Croat said on Tuesday after despatching Robin Haase of the Netherlands in the first round of the French Open 6-2, 6-4, 6-2.
"Sometimes, and actually very often, things can be working very well, but when you don't have enough wins, just at the crucial moments you might be taking wrong decisions.
"So I think it's very important for me at the moment to win as many matches as I can."
Seeded ninth in the tournament, the 26-year-old is the youngest of the six grand slam champions taking to the Paris clay this year and has never gone past the fourth round.
It's a record he hopes to improve.
Russian Svetlana Kuznetsova, the women's champion in 2009, was made to work hard by powerful Dutchwoman Kiki Bertens, winning 6-1, 4-6, 6-2.
Former World No 1 Venus Williams suffered another early French Open exit when she was beaten 7-6(5), 6-1 by fellow American Sloane Stephens in the first round.
It was not a major surprise though as Stephens has reached the fourth round of the claycourt grand slam in the past three years. She will face Briton Heather Watson next.
Seven-time Grand Slam champion Williams, whose best result in Paris is a runner-up spot in 2002 but had not gone past the second round in the last four years, made the better start, opening a 2-0 lead but Stephens proved more accurate.
The 22-year-old broke back and sent the opening set into a tiebreak, which she easily won as her opponent, whom she had never met, netted a forehand.
The 34-year-old Williams never recovered and looked short of energy in the second set as Stephens raced to a 3-0 lead and never looked back, ending the baseline contest with an ace.
"I feel like I had some good practices coming into Roland Garros but sometimes things don't always work out the way you would like," said Williams.
Stephens's biggest fright of the match came in the second game of the second set, when a pigeon came down flying past her as she was about to receive a serve.
"First of all, I didn't know what it was," an amused Stephens, who reached the semi-finals at the Strasbourg Internationals last week, told a news conference.
"I thought it was way closer to me than it actually was. So that was why I screamed so loud. And I don't know, in the moment, things just happen and it was just scary and I was like, ahhh and a scream came out.
"And then she probably wasn't happy because she probably would have hit an ace and it was just a weird moment."