Stan Wawrinka and Gael Monfils waved goodbye to the French Open after they lost in the first round on Monday.

The curtain fell on Frenchman Monfils just before midnight when he lost to countryman Hugo Gaston 6-2, 6-3, 3-6, 2-6, 6-0.

It was the 39-year-old Monfils' final appearance at Roland Garros. Same went for the 41-year-old Wawrinka, who earlier lost to Jesper de Jong 6-3, 3-6, 6-3, 6-4 on another sweltering day.

Monfils and Wawrinka are retiring at the end of the year.

They made their respective French Open debuts 21 years ago.

Wawrinka went on to win three Grand Slam titles, and while Monfils has not reached a major final, his popularity remains high.

Monfils walked out onto Court Philippe-Chatrier to chants of "Ga-el! Ga-el!" He received loud encouragement throughout, demanding applause when he hit spectacular winners and raising his arm when he won the third set.

But he also looked tired, often hunching over with his hands on his knees. After clawing back a two-set deficit he had little energy left against an opponent 14 years his junior.

Monfils was joined in during an on-court ceremony by his former Davis Cup teammates Jo-Wilfried Tsonga, Richard Gasquet and Gilles Simon, and was also praised by his peers.

"For me, you were a true inspiration. A great athlete," two-time reigning French Open champion Carlos Alcaraz said in video featuring several players. "But the most important thing, a great person off the court."

Monfils thanked his wife, Ukrainian tennis player Elina Svitolina, who looked tearful as she listened.

"Without her, I might not be here tonight," Monfils said. "We've been together for eight years, eight beautiful years ... (You) gave me the greatest gift in the world, our daughter. I love you."

De Jong finished off Wawrinka, the 2015 French Open champion and 2017 finalist, with a whipped forehand winner, then urged the fans to applaud Wawrinka, whose face was almost as red as the baking-hot clay.

Temperatures in sun-soaked Paris hit 33 C.

"It's hard, it's hard to say goodbye to you here," an emotional Wawrinka said. "It's because of Roland Garros that I wanted to become a tennis player."

He was given an ovation at Court Simonne-Mathieu, where he was scheduled to face Arthur Fils, but the rising French star pulled out of the tournament with a hip issue.

Wawrinka knows it will be hard to let go — although he still has Wimbledon and the US Open to come.

"For more than 20 years I experienced these emotions, you never want it to stop," Wawrinka said.

"I have given everything for this sport."

His stunning 2015 run to the title saw him defeat heavy favorite Novak Djokovic in the final after downing another all-time great, Roger Federer, in the quarterfinals. Wawrinka stood out that year, as much for his eye-catching pink-checkered shorts as for his destructive backhand.

Those shorts fed into his happy-go-lucky appearance, and he reinforced that image by celebrating with champagne long into the night. But as cavalier as he sometimes seemed, Wawrinka was anything but casual and always trained fiercely hard.

He was hugged on court by tournament director Amelie Mauresmo, before sitting and watching footage of his matches down the years. He was shown video messages from Federer, Rafael Nadal, Djokovic, men's No 1 Jannik Sinner, reigning champion Alcaraz, and Monfils.

At his physical peak, the barrel-chested Wawrinka had huge stamina and was one of the few who beat Nadal, Djokovic, Federer and Andy Murray at the Grand Slams.

Wawrinka beat Nadal in the Australian Open final in 2014 and downed Djokovic again in the US Open final in 2016, meaning all three of his majors were won against the No 1 player. Nadal, however, dispatched him in straight sets in the 2017 French Open final.

He was an Olympic champion in doubles alongside Federer in 2008, and they won the Davis Cup for Switzerland in 2014.

"You are a legend of our sport," said Monfils, who also lost his first-round match at the Australian Open in January.

Monfils reached the semifinals at the 2008 French Open and the quarterfinals on three other occasions.

But, ultimately, he fell short after being touted for a great career following junior titles at the French Open, Wimbledon and the US Open in 2004.

He never won better than an ATP 500 among his 13 titles, and lost 22 finals — including three at Masters level.

His reputation as a showman took precedence over his modest results.

"One of the most likeable, fun guys out there," Djokovic said. "There's no one that doesn't like you, Gael. I think that's your biggest victory."