One of the most exciting players on the circuit, he is also one of the most frustrating.
He's been known to attempt shots between his legs, hit forehands and backhands with both feet a yard off the ground and slide all over the court no matter the surface -- and this all-out physical approach has no doubt contributed to his litany of injuries.
"First of all I want to entertain myself," Monfils, who has only once reached the semifinals of a grand slam, tells CNN's Open Court. "I try to have fun myself, and if people love it I'm more than happy.
"People say, 'Oh, you jump.' Yes, because I want to jump. Yes I play tennis to win but I play tennis first to enjoy as well. When I started to play tennis my mum told me to enjoy."
The craziest shot he's struck?
"I haven't hit it yet," says Monfils, who turns 29 on September 1, the day after the U.S. Open starts. "I think I hit a 360 smash in practice."
It's little surprise that one of his nicknames is "Sliderman," but is Monfils' approach stopping him from adding another title to his resume: grand slam champion?
He won three major titles in his last season as a junior, when he was top of the boys' world rankings, but his best pro performance is making the last four of the 2008 French Open.
His tendency to attempt unnecessary shots to please the spectators -- and himself -- doesn't help his cause, even if his intentions stem from commendable reasons.
"I believe he's so happy to play tennis and to be able to do some shots ... or be part of the show," compatriot Henri Leconte, the 1988 French Open finalist and now a tennis commentator, told CNN.com.
"He wants to do so much for the crowd that sometimes he goes over the limit. Then he loses concentration."
Monfils was criticized by former world No. 1 Andy Roddick when he lost the fifth set 6-0 to Murray at last year's French Open, the American tweeting that Monfils put in a "horrible effort."
"Showboats when winning and rolls over when down," Roddick added.
Then this week at the Cincinnati Masters, Monfils was accused of tanking in the second set of a first-round loss to Jerzy Janowicz.
"To not give 100% and be so blatant about it, I think it's disrespectful," two-time U.S. Open winner Tracy Austin said while commentating for the Tennis Channel, according to Reuters.
Monfils told French newspaper L'Equipe he was simply trying to have fun because he was playing so badly, and he makes no apology for his antics or decision-making.
Born in Paris with Caribbean roots -- like retired French footballer Thierry Henry, his parents hail from Guadeloupe and Martinique -- Monfils is convinced he can win a grand slam.
"Yeah, 100%," Monfils told Open Court. "And I will. I'm 100% sure. It's small details. I'm not that far.
"I need to fix small details and I will do it."
They are indeed bold words from Monfils -- other players might have opted for a cautious response -- although he certainly isn't arrogant. Far from it.
Monfils is, generally, liked by both fans and peers for his easygoing nature and engaging personality, not to mention his often breathtaking shots. Andy Murray called him one of the best, if not the best, athletes to ever play tennis.
It's an impressive package, and yet challenging tennis' "Big Four" in majors has proved difficult for Monfils.
Unlike Stan Wawrinka, who has managed to destabilize the quartet of Roger Federer, Rafael Nadal, Novak Djokovic and Murray at grand slams, Monfils has never really been willing to play an attacking style.
Instead he largely relies on counterpunching -- perhaps most memorably shown in a 71-shot rally at the Australian Open in 2013 with fellow Frenchman Gilles Simon, a match he lost in five sets.
Monfils has only spent about six months inside the elite top 10 during his 11-year pro career. Currently he's ranked 16th.
Of his five titles -- all in the lowest rung of the ATP ladder -- three have come in France, where he feeds off the energy of his home crowd. For someone who likes being in the spotlight, a 5-17 record in finals is underwhelming and slightly puzzling.
Then there is Monfils' propensity of playing fifth sets early at grand slams, which has the effect of wearing him out later in the tournament. Five of his nine grand slam matches in 2015 have gone the distance.
"He has the potential to be top-10 every day," adds Leconte, 52, who was one of the most talented players of his generation. "Maybe he has the chance to win a grand slam. I think he's one of the best athletes on the circuit for sure, with Novak and others.
"The only problem is that he's getting older, everyone is moving forward, and he is just one of the players who want to win a grand slam.
"Then after that you have to work so hard to be there. Getting to the quarters and semis, then after that to the final and winning, it's such a huge difference."
Monfils showcased his skills at last year's U.S. Open, the only grand slam outside France where he has reached the quarterfinals.
Under the lights in the last eight in tennis' largest regularly used stadium, Monfils led Federer by two sets and held two match points before the Swiss rallied
Nonetheless he enjoyed the experience and has only fond memories of the season's final major.
"It's always an honor to play on Arthur Ashe stadium. I used to love (Arthur Ashe)," Monfils said of the three-time grand slam winner, who died aged 49. "The crowd is unbelievable. One of the best atmospheres ever.
"The energy is crazy. I can't really explain it but I love the people there and the crowd gives me a lot.
"It's the first slam where I flew with with my mum. I always wanted to see New York when I was a kid. When you look far back, I was watching the U.S. Open and now to go to New York and visit the city and play at the U.S. Open, for me it's just crazy."
Monfils still has a few years left before he retires.
When he does call it quits, Monfils claims he might pursue watchmaking.
"Strange, right?" he said. "I love watches, the mechanism. I've learned a bit about how you make a watch, actually, and it's something that I would explore maybe after my career."
And we've learned more about what makes Monfils tick.