To say that PSG were cruising would be an understatement. With a quarter of the game to go, they were 5-0 up against a Montpellier team that had been playing with 10 men since their goalkeeper, Dimitry Bertaud, had been dismissed in the 17th minute. Kylian Mbappé had already scored his goal and this was PSG’s ninth game in four weeks. So, with a trip to Borussia Dortmund on the horizon, Thomas Tuchel decided to give him some respite. It was not just a good idea; it was necessary.

Nevertheless, Mbappé was clearly frustrated to be substituted. As he walked off, he tried to bypass Thomas Tuchel on the touchline. When the manager began to reason with his player, Mbappé initially attempted to ignore him before talking back. After they had engaged in some debate, Mbappé walked towards the bench, muttering to himself and dismissively waving his hand over his shoulder at Tuchel.

He was still grumbling after the match when he made his way to his private box with his relatives, refusing all requests for selfies from supporters. Although it was a fairly minor incident, tempers were undeniably raised and Mbappé’s petulance, even disrespect, was clear. Speaking after the game, Tuchel said the incident was “not good” because it “opens up discussion” and “distracts our minds”. “I’m not angry,” he said. “I’m sad.” Ángel Di Maria backed up his manager, saying: “There are boys on the bench who want to come on and have the ability. He needs to get that.”

This is not the first time Mbappé has acted in a way that suggests his ego is inflating and his temper is shortening. Something similar happened in the reverse fixture against Montpellier in December, when Mbappé was substituted off and tried to ignore Tuchel’s existence. When he was voted the Ligue 1 Young Player of the Year last season, he used his acceptance speech to alert other clubs to his availability, saying: “I feel it is perhaps the moment to have more responsibility. I hope that can maybe be at Paris Saint-Germain. That would be a great pleasure. Or perhaps elsewhere with a new project.” He elaborated even further after the ceremony, saying: “When you are at such an occasion you can send messages. I think I have sent mine.”

‘Inspired by KM’: Mbappé takes aim at hitting his most creative target yet | Paul Doyle Read more

This burgeoning bolshiness contrasts with his behaviour away from football. Last week, Mbappé launched a charity, Inspired by KM, which will sponsor 98 children from Paris to fulfil their dreams. “We will support them until their working lives begin,” he said at the launch, adding: “I didn’t set this up to delegate. I am going to invest myself in this to the maximum.”

Although his assertion last month that he is “now a superstar” was a little on the nose, Mbappé always comes across as affable and friendly in interviews, mirroring the cheeky chap who emerged at Monaco in 2017 rather than the sulking youngster who kicked up a fuss this weekend. His Instagram account portrays a relaxed, socially conscious young man who is aware of his position and status. He has posted recently about the Australian bushfire crisis, saving the Amazon rainforests and voting in the European elections. He contributed €60,000 to help find Nantes forward Emiliano Sala and pilot David Ibbotson after their plane tragically disappeared last January and he donated all £275,000 of his match fees from France’s 2018 World Cup win to charity.

As a result, the darkening of his mood on the pitch is a little jarring. Could the poisonous sense of entitlement that has long tarnished young PSG players (such as Adrien Rabiot) be infecting him? Is Mbappé simply starting to believe his own hype? The boyish confidence of the 18-year-old who exploded with upstarts Monaco may now appear more conceited in the context of PSG’s all-consuming dominance.

His tightening friendship with Neymar may be having a detrimental impact on him. Neymar is exquisitely talented but, for a man who turns 28 this week, he can give the impression of being very spoiled. He struck a fan in the face while collecting his runners-up medal after last season’s Coupe de France final; he repeatedly challenged former coach Unai Emery; and, just this weekend, he told referee Jérôme Brisard “Speak French? My ass!”. He held his birthday party in a nightclub in Paris on Sunday evening, two nights before his team’s next fixture (an event that Mbappé did not attend).

Mbappé’s altercation with Tuchel naturally fosters speculation about his career path. He was born in Paris and seems to be content at PSG, but he will eventually look to leave. A fortnight ago he said he was “100% with the club” before adding that “at the end of the season, we will see”.

Mbappé would command a mammoth transfer fee and help alleviate PSG’s ongoing worries about FFP but the desire to sell simply isn’t there, meaning he would have to agitate strongly for a move. Are these tantrums the beginning of a calculated attempt to leave? Make no mistake, Mbappé is intelligent and everything he does is deliberate and considered.

Wherever his sporting future lies, Mbappé the man and Mbappé the footballer seem to be diverging. Many footballers are generous and socially aware – England players have long donated match fees to good causes and Neymar has set up a charity to provide more opportunities for disadvantaged children and their families in Brazil – but Mbappé’s breakthrough in 2017 was so exciting because he combined extraterrestrial ability on the pitch with an affable, professional and work-focused personality that seemed capable of inspiring any kid from any background to pursue any dream.

Who are we to tell Mbappé how to live his life? We simply note that, if that personality fades as the spotlight brightens, France might lose la tête d’affiche that both parents and children admired in equal measure.

Talking points

There is still magic in the French Cup Read more

• Claude Puel is in trouble. Four wins in six at the start of his St Étienne reign seemed to have rescued the club from relegation fears but an abhorrent 3-1 loss at promoted Metz on Sunday was their fifth defeat in six Ligue 1 games. The recent returns from injury of key forwards Wahbi Khazri and Denis Bouanga will help, but being in 15th place is a concern. A return to Europe looks increasingly unlikely. Their next two games against theoretical direct rivals Marseille and Montpellier could decide Puel’s fate, a dismissal would represent his third in less than four years.

Facebook Twitter Pinterest These are tough times for Claude Puel. Photograph: Damien Meyer/AFP via Getty Images

• The Coupe de France enjoyed another glorious week. Fourth-tier Epinal caused the biggest upset of the competition this season, beating Lille, who finished second in Ligue 1 last season. Belfort, also a fourth division club, knocked out Montpellier on penalties; Rennes and Angers took their nine-goal thriller into extra time before Jérémy Gélin scored a 110th-minute screamer to take Rennes through. Tiny National club Pau, who ousted Bordeaux in the previous round, gave PSG a better game than many top flight clubs have managed of late, only losing 2-0. Belfort v Rennes and Epinal v St Étienne are the pick of next week’s quarter-finals.

Ligue 1 results

Quick guide Ligue 1 results Show Hide Nice 2-1 Lyon

Metz 3-1 St Étienne

Bordeaux 0-0 Marseille

PSG 5-0 Montpellier

Amiens 0-0 Toulouse

Angers 1-4 Reims

Dijon 3-0 Brest

Nîmes 3-1 Monaco

Strasbourg 1-2 Lille

Ligue 1 table