Doue comes from strong footballing stock, with his 22-year-old brother Guela playing right-back for Strasbourg after leaving Rennes, while cousin Yann Gboho is a talented attacking midfield player at Toulouse.

He is of French-Ivorian descent, making his full France debut in the 2-0 win against Croatia in the Uefa Nations League quarter-final in March, again scoring a penalty as they went through after a shootout.

Brother Guela has other international allegiances, winning international caps for Ivory Coast.

The brothers developed under the watchful guidance of father Maho, who worked with them every day - organising training sessions outside the work they were doing at Rennes, and still exerts a wise and steadying influence on their careers.

Some eyebrows were raised when PSG paid such a large fee for Doue in the summer, but Rennes are as good at driving a hard bargain as they are producing young gems.

They have history, selling Doue's current team-mate Ousmane Dembele to Borussia Dortmund, Eduardo Camavinga to Real Madrid and Mathys Tel, now on loan at Tottenham Hotspur, to Bayern Munich.

Arsenal, Chelsea, Spurs, Manchester United and Newcastle United all showed serious interest in Doue - but it came down to PSG or Bayern.

French football expert Julien Laurens told BBC Sport: "PSG probably would have liked to pay about £34m and tried to get it down, while Bayern were happy to pay more than £50m - but he wanted to go to PSG.

"It might have felt a little high, as it was when PSG paid £34m for Bradley Barcola after six good months as Lyon, but there is a premium, as there is in England, when you sell from French club to French club.

"The key was that Luis Enrique and sporting director Luis Campos were both convinced they were getting a superstar in the making.

"Doue is so talented, strong mentally and physically. At PSG, they say he's got rugby players' legs because the bottom half of his body is so strong.

"They knew in Paris it would take time but they were ready. Luis Enrique was so happy to sign him. He was the player he wanted. They were aware he may need half a season, a season, but were happy to wait if needed."

Despite these new burdens, PSG insiders have been hugely delighted with Doue's dedication and professionalism.

"The club have been very impressed with his fitness work, gym work," said Laurens.

It was the same at Rennes, with former coach Bruno Genesio saying: "Away from the pitch he's a dream: easy, calm, with a streak of leadership while still asking for advice. He's both care-free and conscientious in his work. He's already a pro in his head."

Doue first hit the radar when France won the European Under-17 Championships in Israel in 2022, then he was on the bench for the Olympic final in Paris two years later, coming on after 77 minutes when France lost 5-3 to Spain after extra time.

The Olympics arguably contributed to his slow start at PSG, lacking a proper pre-season, but he has been the beneficiary of careful management by Luis Enrique - who has worked individually with Doue, encouraging him through his quiet start.

He has only made five starts in the Champions League this season, with seven appearances as a substitute, scoring three goals and adding two assists.

It was at Anfield where he made his mark, coming on after 67 minutes to deliver a performance of remarkable maturity, capping it by being entrusted with the spot-kick that sent PSG through.

Doue has been kept out of the limelight by PSG, while the calming, grounded influence of his family is a huge factor.

Laurens explained: "The dad, Maho, is very influential in everything they do. Some families think their son is the next Cristiano Ronaldo, oblivious to everything going on on the pitch, but they were realistic.

"After the Arsenal game, where he did look out of his depth, they said he wasn't ready for the big step up another level. They understood he had to work a lot, he had to mature. They were very realistic about what he had to do. It was very impressive, very refreshing. They understood."

Doue has also had to adjust to life in the Paris goldfish bowl, away from quieter Rennes.

He lives in the fashionable Boulogne-Billancourt area and Pierre-Etienne Minonzio, based in Paris with influential sports paper L'Equipe, told BBC Sport: "Recently he was in a very popular shop. He was there just looking for a book when somebody spotted him.

"It was totally normal because he is so young, but maybe he did not understand it is going to be hard for him to be in crowded places in Paris.

"It is good that he thought he was not a star, but he probably hasn't been back. He's very into performance, wanting to be the best. If you tell him one of the next steps in his evolution is not to be seen so much in public, he will understand no problem."

It took until December for Doue to score his first PSG goal, in the 3-0 win away to Red Bull Salzburg in the Champions League, but since then it has been lift-off.

"He was born in 2005 and in France's football world, everybody said the big thing in France born in 2005 was Mathys Tel, now at Spurs," Minonzio said.

"For his generation, Doue was not the one because he was less talented than Tel, but when you get older the psychological attributes make a lot of difference and Doue has shown incredible mental strength.

"Everybody thought for this generation of players Tel would be the main guy, but now the talk is Doue."

And to crown his development, Doue was called up by France coach Didier Deschamps, overtaking two other players regarded as potential members of the new generation, Lyon forward Rayan Cherki and Maghnes Akliouche from Monaco.

Laurens said: "It all changed from a wider perspective after his debut for France. He was outstanding against Croatia. He was not scared, demanded the ball, scored a penalty. This guy had arrived."

In France, the general view is that Doue's form left Deschamps with no option.

Minonzio says: "Deschamps is obsessed with the Champions League. He wants his players to show him their ability in high-level games. He is always a little hesitant to take players who are very good in French league games but don't play in Champions League.

"It was obvious in March that Deschamps had no choice other than to select him."

Villa Park is the next step on his development. And while the sky seems the limit, there is still caution.

"A few months ago I would have told you the face of the new PSG would be Warren Zaire-Emery. Just 19, Parisian, lots of talent." says Minonzio.

"Everything he did was so impressive but you always have to wait to see how they react when there are problems.

"This is the fascination with Doue in France. We still don't know how good he will be, but at the moment he is free, does not ask any questions and life is good. He has been incredible."