Jack Draper, seeded fifth, fought back after losing the first set 3-6 to an animated Mattia Bellucci, to take the next three sets 6-1 6-4 6-2 and move into the second round.
The British men’s number had previously lost on his first two appearances at Roland Garros but is now a genuine contender on the clay.
He joins Sonay Kartal, Emma Raducanu, Katie Boulter and Cam Norrie in the second round
Draper said after winning he “trusted his tennis would click into place” was the key to earning his first career French Open win.
After beating 68th-ranked Bellucci, Draper said he is still learning the benefits of being more patient in the five-set format at Grand Slam events.
Cameron Norrie also claimed one of his best career victories with a five-set win over world number 11 Daniil Medvedev in a topsy-turvy French Open first-round match, to win 7-5 6-3 4-6 1-6 7-5 in a match lasting almost four hours.
Medvedev served for the match at 5-4 in the fifth set but could not hold off Norrie, who then won three games in a row to seal victory.
Norrie launched his racquet into the air in celebration after a long Medvedev forehand confirmed his victory.
“There wasn’t a lot on my mind on match point,” 29 year old Norrie said.
“I felt that he was a little tentative but honestly, it was a crazy match.
“I think I deserve a diploma for beating Medvedev because he’s beaten me the last four times. It was an unreal match.”
The Brit will face Argentine lucky loser Federico Gomez for a place in the third round.
