Novak Djokovic made the second round of the French Open after beating Brazilian qualifier Rogerio Dutra Silva.
The former world number one, seeded 20th at Roland Garros, went 2-0 down at the start of the first two sets but recovered to come through 6-3 6-4 6-4.
The injury-hit Serb, 31, has not won a Grand Slam title since his victory in Paris in 2016.
Meanwhile Stan Wawrinka, another former champion who has struggled with injury, lost his opener.
The Swiss 23rd seed, who overcame Djokovic in the French Open final in 2015, was beaten 6-2 3-6 4-6 7-6 (7-5) 6-3 by Spaniard Guillermo Garcia-Lopez.
Elsewhere, Austrian seventh seed Dominic Thiem overcame Ilya Ivashka of Belarus 6-2 6-4 6-1.
World number 12 Djokovic said before the tournament that his confidence had been knocked after suffering a recurring elbow problem, which required surgery in January.
He returned to training in March and fell to successive first-round defeats at Indian Wells and the Miami Open.
But the 12-time Grand Slam champion reached the semi-finals of the Italian Open earlier this month and looked fairly comfortable against Dutra Silva, the world number 134.
The Brazilian got off to the best possible start by breaking his opponent in the opening game, before Djokovic got into his stride.
Dutra Silva had his opponent rattled in the third set after they exchanged breaks, and Djokovic slammed a loose ball against the advertising boards in anger before apologising to the crowd for his reaction.
In the end, the Serb brought up three match points and served it out at the second attempt.