One of the most damaging things that can happen to a player's career is winning a World Cup. Once you've climbed the game's highest peak, where is there left to go? Most of the French world champions of 1998 went on to have dreadful league seasons in 1998-99. Their captain, Didier Deschamps (now France's coach) later admitted to feeling "physical and moral apathy" after lifting the trophy. In the next World Cup, the French were knocked out in the first round, the fate of four of the past five teams to win the trophy.

Winning it as a young player is probably worse. In 2002, the Paris St. Germain forward Ronaldinho, 22 at the time, became world champion with Brazil. He then briefly flowered into the planet's best player, but four years later was spiralling downwards.

So it's natural to worry now that another young PSG forward, Kylian Mbappe, France's 19-year-old world champion, has got his career upside down. Winning the World Cup and scoring in the final was "the absolute dream," he has said. It might seem hard to go from that to an away game in a small French town, or even Anfield, where PSG went down 3-2 to Liverpool in matchday one of the Champions League group stage. Mbappe had a lackluster game in England, scoring once but losing possession for Roberto Firmino's last-minute winner. Nonetheless, mere weeks after Luzhniki, the Frenchman already looks well equipped on the long term to surmount the post-World Cup curse.

We're still just getting to know Mbappe, and the fly-on-wall documentary about France at the World Cup, shown on the French TV channel TF1 days after the final, was a help. He emerges from the film as a disciplined, popular squad member whose teammates enjoy teasing him about his age. In one scene, shot after France's lucky 2-1 win in their opening game against Australia, a furious Deschamps ("I don't want anybody laughing!") lays into his assembled players for the lack of high-intensity runs. He then turns to Mbappe and says, "Kylian is the one who did least: 3 percent." (In other words, only 3 percent of Mbappe's running in the game was at high-intensity.)

The scene hints at the reign of stats talk in modern changing rooms. But what comes next offers a window into Mbappe's world. There he is, a teenager, who has just disappointed in his first World Cup game, and has been shamed in front of his teammates, yet afterwards he tells the camera, with his characteristic calm and articulacy: "He did what a coach does when his team doesn't do what he asks for and expects."

Mbappe was able to handle Deschamps' attack because he has lived like a high-performance professional since he was 14. His father, the paid youth coach at his local amateur club in the Parisian suburb of Bondy, had raised him with the idea that what matters is always the next match. So he was as prepared as anyone can be for being a world champion at 19. Winning the World Cup, Mbappe said the night of the final, was "already good," but it was merely a stage in his career. He pointed out to TF1 that his life has a different shape from other people's: because he rises so quickly, he reaches a new level every six months or year. "Winning the World Cup is just going up another level," he said.

He added, "Playing high-class soccer is not satisfying yourself with what you have. It's winning, winning, winning. People will forget that you are a world champion. You are Kylian Mbappe of PSG, and you need to prove that you have your place in the team. Every year you have to go back to zero, as if you had done nothing before."

After Mbappe's first game at the 2018 World Cup, head coach Didier Deschamp tore into his young player, but it wall worked out in the end for both of them. getty

Winning the World Cup hasn't changed his daily life either, because he was already living like a luxury prisoner at home, too famous to go outside. (A French friend proudly showed me a video of his 5-year-old son bothering Mbappe on a Corsican beach during the player's brief summer holiday. Mbappe, although trying to relax with friends and family, politely doles out the autograph.) Playing soccer is almost his only release. He marvels when he sees the tension on other players' faces, because he doesn't feel it himself. Everything has come easily to him, without great sacrifice, he once said.

When he and his fellow world champions Presnel Kimpembe and Alphonse Areola returned to PSG for preseason training, the rest of the squad formed a semi-circle and gave them an ovation. The trio had achieved a feat that will probably always elude even their teammate Neymar, but Mbappe cannily told a TV camera, "Neymar is more of a superstar than I am. He worked for years at Barcelona to achieve that status."

On August 18, Mbappe made his first appearance since the World Cup final, but this time in a village stadium in Brittany. Coming on at half-time at Guingamp, with PSG 1-0 down, he scored twice to turn the game. Several of Guingamp's players were visibly honored to be on the same field as him. One of Mbappe's new challenges is working out what to do when six opponents all ask you to swap shirts. So far this season, he has four goals in two and a half league games, which makes him the first teenager in 45 years to reach 30 career goals in the French league. He is also, among many other things, the first teenager to win a World Cup since Italy's Giuseppe Bergomi in 1982; the first to score in the final since Pele in 1958; and the second-most expensive player in history, after his teammate Neymar. (PSG paid Monaco €135 million for him, with another potential €45 million in bonuses to come.)

Still, the guy remains human: on Sept. 1, he was sent off in the final minute against Nimes after petulantly pushing to the ground an opponent who had fouled him. When you're on top of the world, it's only natural to feel outraged when anyone rattles your pedestal. After the game, he was still defending himself like a hot-headed teenager: "If I could do it again, I would." Later, presumably advised by PSG and/or his father, he apologized to PSG's fans on Twitter.

While there's a risk that the World Cup will damage his career, or that like some other explosive strikers he will peak very young, there's also a decent chance that Mbappe will only get more dangerous. That's because he is being given a more dominant role on the field. Last season, and at the World Cup, he played for PSG and France as a winger. Now, in both teams, he is moving towards the center. PSG's new coach Thomas Tuchel seems to favor a 3-5-2 formation, with Neymar at No. 10 behind a two-pronged forward line of Mbappe and Edinson Cavani.

For France, Mbappe still starts on the right wing but is encouraged to pop up in the center more than before. Soon he may get the central role permanently, because France's centre-forward Olivier Giroud had a poor World Cup and turns 32 on Sept. 30. Imagine a French forward line of Griezmann and Mbappe, supplied by Nabil Fekir at No. 10. That could be better than the World Cup side.

It was scary watching Mbappe in France's 2-1 defeat of the Netherlands on September 9. Surrounded by 21 top-class athletes, he looked much more athletic than anyone else on the field. His markers stood off him, terrified of his speed, which meant he always had a couple of meters of freedom. Any ball in his general vicinity was dangerous, as he can win possession even when starting five meters behind a defender. Forever in motion, and accelerating when receiving the ball, he tapped in his eighth goal for France this year. Afterwards one of the French world champions of 1998, Christophe Dugarry, said, "I think that the people who will see him these next 10 years are enormously lucky. Like those who saw Maradona, Pele."

That might sound like high praise, but imagine where Mbappe would be if he manages to go up just one level.