Novak Djokovic launched his quest for a record-breaking 23rd men's grand slam singles title with a no-nonsense 6-3 6-2 7-6 (7-1) victory over debutant Aleksandar Kovacevic.
Djokovic, twice the champion at Roland Garros, has made a stuttering start to the clay-court season and was beaten by Denmark's Holger Rune in the quarterfinals in Rome this month.
But he breezed through the first two sets of the French Open on Monday before encountering resistance from 24-year-old Kovacevic.
The American's lack of experience was exposed in the tiebreaker on the world's biggest clay court and Djokovic ended the contest with a sizzling service return on his first match point.
"It's always a pleasure to come back here, one of the best tournaments in the world," said Djokovic, who made his Roland Garros debut in 2005.
"I'm very motivated to go far here, all the way I hope."
Djokovic, champion in 2016 and 2021, will next face Hungarian journeyman Marton Fucsovics for a place in the third round.
Italian veteran Fabio Fognini, 36, rolled back the years on the second day to take down 10th seed Felix Auger-Aliassime in the first round.
Fognini's 6-4 6-4 6-3 win meant the Canadian became the first top-10 player in the men's draw to be knocked out of the tournament.
Fognini's reward is a second round clash with Australia's Jason Kubler, who beat Spain's Facundo Diaz Acosta in five sets.
But after his latest defeat, Auger-Aliassime said he needed to prioritise his health.
The 22-year-old pulled out of the Lyon quarter-finals last week with a shoulder problem and revealed that he had also been unwell.
"The shoulder is not great, but that wasn't the issue today. I got a bit sick last night, didn't really sleep.
"I tried to warm up. I tried to see the doctor, see what I could take, but after one set, just cramping and just can't move anymore.
"I think I must go home. I have to do a battery of tests to see why I was sick here, why I was sick a week ago and see what's happening."
World No.1 Carlos Alcaraz looked in ominously good form as he eased past Italian qualifier Flavio Cobolli 6-0 6-2 7-5.
The 20-year-old, who missed the Australian Open with a leg injury, was especially ruthless as he raced through the opening set.
British No.14 seed Cameron Norrie made it through but it was a close shave against French wildcard Benoit Paire.
The mercurial Paire, whose last win in the main draw of top-tier tournament dates back to August, made the most of his wildcard invitation but was punished for 81 unforced errors.
The extravagantly bearded Paire, 34, also hit 70 winners, to the delight of the French crowd, but went down 5-7 4-6 3-6 6-1 6-4.
"It was an amazing match, he played really well and I'm glad to see him compete like that again," said Norrie.
"We put on a good show in a great atmosphere. For the sport it was amazing."
Dominic Thiem took his main draw spot after the withdrawal of 14-times champion Rafa Nadal but the injury-plagued Austrian fell to Argentine Pedro Cachin who won 6-3 6-2 6-7 (7-1) 4-6 6-2.
Veteran Stan Wawrinka set up a second round clash with Australia's Thanasi Kokkinakis when he outlasted Spain's Albert Ramos-Vinolas in five sets which took four hours and 35 minutes to complete.
Zhang Zhizhen became the first Chinese man in the Open Era to win a main draw match at the French Open when Dusan Lajovic retired while down 6-1 4-1.
The evening match on Court Philippe-Chatrier was a brief affair, Italy's No.8 seed Jannik Sinner dazzling under the floodlights to swat aside Frenchman Alexandre Muller 6-1 6-4 6-1.
With agencies
