Third seed Rafael Nadal began his bid for a 21st Grand Slam men's singles title with a straight-set win against Australia's Alexei Popyrin.
The 34-year-old Spaniard, going for a record-extending 14th triumph at Roland Garros, won in straight sets 6-3 6-2 7-6 (7-3).
Serbian top seed Novak Djokovic also eased through to round two, beating American Tennys Sandgren 6-2 6-4 6-2.
Russian seventh seed Andrey Rublev is out after losing in five sets to German world number 42 Jan-Lennard Struff.
Rublev's defeat means there is one less obstacle for Nadal as the Spaniard seeks to set an outright record for major men's singles titles - a milestone he presently shares with Roger Federer.
With the seedings based on the world rankings, Nadal is third behind Djokovic and Daniil Medvedev this year and has been landed with a potentially tricky draw.
