Gael Monfils overcame cramping and a four-game final set deficit to win his first match in nine months in a French Open late night blockbuster, dubbing himself "totally crazy".
The 36-year-old crowd-pleaser, who has slumped to 394 in the world rankings after battling a crippling foot injury, defeated Sebastian Baez of Argentina 3-6, 6-3, 7-5, 1-6, 7-5 in a first round tie which ended in the early moments of Wednesday morning.
A semi-finalist at Roland Garros back in 2008, Monfils came back from 0-4, 30-40 in the decider to stun an opponent 14 years his junior and ranked at 42.
"It's crazy. I talked to myself (after the fourth set), and I said, Don't you worry, I'll recover, and I'll beat him, I'll kill him during the fifth set," said Monfils.
"Think about this, I'm totally crazy."
Monfils could hardly walk in the final set as the intensity of the occasion sparked cramping in both legs.
His winning backhand brought the Court Philippe Chatrier crowd to its feet before a sobbing Monfils collapsed onto the red clay surface.
He saved 11 of the 20 break points he faced in a tie which stretched the best part of four hours.
Monfils's last win on tour came in Montreal in August 2022 before a plantar fascia rupture in his right foot sidelined him until March this year.
It was the latest in a long line of physical problems endured by the Frenchman in his 19-year professional career.
In that period, he has missed 13 Grand Slams with a series of injuries, including right knee, right shoulder, left wrist and most recently right foot.
"When I was back on the tour, I thought, okay, I'll wait for Roland Garros," said Monfils.
"I didn't even expect to win this match. My objective is to be fit so that I can have long matches."
He said he tried to ignore the cramping which spread to both legs by the time the fifth set was played out.
"I was really hurt but that's why we're called high-level sportsmen, because from time to time, you manage to overcome the pain.
"I had cramps, but quite high in the thigh. So I could go right, left, right, left. I could do this.
"But his dropshots really hurt. When he did the dropshot, I was laughing, I thought, oh, no, now two legs, it's going to be complicated."
Monfils ranked his win as being in the "top two" of his career after a similarly dramatic five-set duel to defeat Pablo Cuevas at Roland Garros in 2015.
However, his path through this year's French Open is about to get a lot tougher as his second round opponent is world number six Holger Rune.
Before that clash, Monfils will watch his wife Elina Svitolina attempt to make last 32 when she faces Australia's Storm Hunter later Wednesday.
Svitolina, a former world number three now at 508, is back on tour after maternity leave when she gave birth to Skai, her daughter with Monfils.
At the weekend she won a 17th career title and first as a mother with victory in Strasbourg.