Swiss third seed Stanislas Wawrinka lost his opening round match against Guillermo Garcia-Lopez.
Number 41st-ranked Spaniard stunned the 2014 Australian Open champion 6-4, 5-7, 6-2, 6-0 on the Court Philippe Chatrier.
Garcia, who has never moved past the third round at the Roland Garros, now faces France’s Adrian Mannarino in round two.
“I was trying to find my game, trying to be aggressive, trying to find anything, and I didn’t,” said Wawrinka.
Fresh from winning his third career singles title in Casablanca, the 30-year-old quickly snuffed out Wawrinka’s early break of serve on his way to taking the opening set in 36 minutes.
The Swiss number one, 29, leveled the tie in the second set, but struggled thereafter, as he could barely keep the ball in court, winning just two games in the final two sets.
“I think I’m not as overwhelmed by emotions as I used to be… I fight on every point,” Garcia Lopex said.