He arrived with less hair and no promotion. In his first match on Tuesday a couple of doubtful line calls got to him. Really got to him.
He had just begun to hit some big shots late in the first set. After venting frustration he couldn't get his head back under control.
He lost his sting, sprayed balls wide and dropped the set.
Watching him, every weekend duffer knew the demons he was fighting. They were muttering, "Why am I here? What do I care? ... Wish I played golf ... or on a day like this, gone to the beach."
He got over it. In the second set and the third he turned on the power and accuracy of players we seldom see here and gave us moments of artistry seldom seen anywhere.
Two nights later it happened again when tough Tommy Haas got into his head, taking the towel too long once Monfils found some momentum on serves.
Mostly though, Monfils was battling his own mind, sloping around, under-hitting, doing up his shoes one time as Haas was smashing. It is called showmanship but it was not that calculated. It is just the way he is.
He thumped down aces when he needed them and surprised himself as much as Haas with occasional sizzling returns that kept him in it. At the end he thanked heaven for his good fortune and the crowd. He said he travels alone and the crowd was his only support crew.
Little wonder when you read what a former French player, Henri Leconte, said of him last year: "He has a strange way of training, thinking about sports, about his life, his entourage, his everything. It's a nightmare. He doesn't know where to go. He's lost.
"One day he wants to be a tennis player, the next day he wants to be a soccer player. The day after that he wants to be a basketball player. He's losing time. He could be in the top 10 easily - if he works."
Maybe, but it is wonderful to watch a supremely talented sportsman who is as brittle as anyone in his head. I'd sooner follow his progress than any of the well-honed craftsmen who will beat him.
Winning is not everything. Those who say it is do not really find much pleasure in it.
The new press box in the partially renovated Stanley St stadium has some quotes from great players on a wall. One of them, ascribed to Jimmy Connors, says, "I hate to lose more than I love to win."
That bleak attitude infects our appreciation of most sports, particularly rugby. Auckland teams play rugby rather like Monfils plays tennis. In good years they have produced feasts of running and passing that sweep like blue tides across Eden Park. In bad years the magic deserts them and so do the spectators.
Gareth Morgan, who has invested some of his wealth in the Wellington Phoenix, has been widely derided for suggesting they should play a more entertaining style of soccer.
Winning, say the critics, is what counts.
If that was true they would have stopped writing about New Zealand cricket years ago.
The loyalty of Warriors supporters too says it isn't true.
Even losing can be glorious, as the All Blacks discovered when, with all the season's trophies in their cupboard, they lost to an inspired England team that payed them the ultimate tribute of playing a fast, accurate All Black game.
Every January we get a glimpse of the world tennis circuit, not on television where most of the sweat and speed of the game are lost in transmission, but at courtside where you can see it all.
The ASB Classic last week was a revelation. Women have begun to hit a lot heavier in the past year or two and Marina Erakovic has developed a big forehand that lets New Zealanders watch her with hope.
But mostly we have to make heroes of those who bless us briefly with their presence. If Gael Monfils resurrects his career from here - even though he didn't make today's final - we can adopt him.
He is sublime and human. It is not just winning that counts in sport, it is not even the style of winning, it is the struggle. Sport, even at this level, can be a simulation of life.
