The Serbian, coming back from an injury absence which has seen him dip out of the world’s top 20 for the first time since he was a teenager, dropped his serve in the opening game of the match.
But it proved a false alarm as the 12-time grand slam winner brushed aside his Brazilian opponent 6-3 6-4 6-4.
“You don’t always get to feel your best but all you can do is try and get the best out of it,” the Serbian told a packed Philippe Chatrier court.
Djokovic, who didn’t play a competitive match between Wimbledon last July and Melbourne, endured a tough run into Roland Garros. He fell in the second rounds at Barcelona and Madrid before reaching the semi-finals in Rome, where he was defeated by world number one Rafael Nadal.