Real Madrid’s long-awaited signing of Kylian Mbappe has plenty of upside for the reigning Spanish and European champions — but there are some question marks.

One of them is how Mbappe fits into the starting line-up, given his preferred position is on the left wing, which is where Vinicius Junior, last season’s 24-goal top scorer, plays. The other is how the 25-year-old Frenchman will gel with an established dressing room — an aspect the La Liga club looked at in January when they again started to seriously consider signing him.

The Athletic has previously detailed how head coach Carlo Ancelotti plans to use a flexible 4-3-3 system, with Mbappe playing through the middle, Vinicius Jr on the left and Rodrygo on the right. This will become a 4-4-2 in defence, with Mbappe and Vinicius Jr as the front two and Jude Bellingham moving to left midfield.

That leaves the personality question. Madrid did not want Mbappe to enjoy the degree of power he had at previous club Paris Saint-Germain after renewing his contract there in 2022. They also feared giving him an excessively high salary could raise suspicions among a harmonious group of players. Reports have suggested Mbappe will be paid a signing bonus in the region of €100million ($109m; £84m) then a €15m salary.

This current set of Madrid players is considered one of the most tightly knit of recent years. Sources close to the dressing room — who, like all those cited in this article, asked to remain anonymous to protect relationships — have said the atmosphere is the best they have ever known and recognised they had not felt the same way in previous years.

That was something referred to by the recently retired Toni Kroos when he was asked at an event last week if he would stay in contact with any of his former Madrid team-mates.

“Yes, I have a personal relationship with many of them,” the German midfielder said. “Last season was not only very successful but we also had a top dressing room — I can’t say the same for every team I played for. They are people I want to keep in touch with.”

Mbappe was presented to much fanfare last week (Alvaro Medranda/Quality Sport Images/Getty Images)

There have been signs of that during the players’ summer holidays.

As in 2023, Vinicius Jr invited a selection of his club team-mates to home city Rio de Janeiro after Brazil’s Copa America quarter-finals exit against Uruguay this month. Many could not go because of family commitments or scheduling issues around international tournaments, but Eduardo Camavinga, Ferland Mendy, Eder Militao and Rodrygo went.

The players attended a charity event for the winger’s foundation, the Instituto Vini Jr — into which he has invested €1.3million over the last year to help more than 3,500 children — and enjoyed a few days of rest, parties and playing football against each other. They were joined by people from their entourages and other high-profile figures from the world of sport and elsewhere, such as the Boston Celtics NBA star Jaylen Brown and singers Ozuna, Rauw Alejandro and Ludmilla.

Mbappe was among those invited along with Vinicius Jr’s countryman, friend and now-Madrid team-mate Endrick. But both were due to be officially unveiled at the club’s Santiago Bernabeu home stadium after their respective involvements in the European Championship and the Copa America — Mbappe was unveiled last Tuesday; Endrick will be this Saturday — and needed to deal with the logistics of their new life in Spain.

At his opening press conference, Mbappe confirmed that Vinicius Jr had played a role in him finally joining Madrid. He was asked which players had spoken to him about the club before his arrival from PSG.

“I had all the French players, who always told me and explained to me that it is the best (club) in the world,” Mbappe said. “Also Vinicius, who asked me to come, and told me that we would play together in attack. Thank you to them, because it’s always a good thing that they want me to play with them.”

Mbappe with now-Madrid team-mates Camavinga and Tchouameni in France training (Franck Fife/AFP via Getty Images)

Several players showed public support — whether implicit or explicit — for Mbappe’s signing before it was made official.

When rumours linked Madrid with the move last year, Rodrygo posted a photo of himself partying with Mbappe in the August. And, once the deal was announced, there was a big reaction on social media from the whole squad.

Sources at Valdebebas, Madrid’s training ground, said Mbappe has made a good impression, describing him as “intelligent” and “cheerful”. The club offered him lower terms this time than those in their failed 2022 proposal, although his base salary is among the highest in the squad (and with his signing bonus included he is by far their best-paid player).

Mbappe made the right noises in his first press conference, saying he would play where Ancelotti asked him to and adding that he was not thinking about taking the No 10 shirt worn by Luka Modric for the past seven seasons, out of respect for the long-serving Croatian midfielder (he’ll wear the No 9).

So there are good signs — and it is worth considering what happened when Bellingham, another big personality, joined Madrid last year.

Initial reports suggested Bellingham and Vinicius Jr did not get on, but that was soon proven wrong. They sometimes took the same car to training and Vinicius Jr celebrated some of his goals by recreating the Englishman’s ‘open arms’ celebration. When Bellingham was interviewed by the club’s official TV channel during Madrid’s La Liga title celebrations in May, he said, “I’m here, with the best player in the world” as he embraced Vinicius Jr.

The Brazilian called Bellingham ‘Belligol’ in that interview, one of several nicknames that is within the squad.

Goalkeeper Thibaut Courtois is 6ft 7in (200cm) so is known as ‘Jirafa’ (Giraffe), Antonio Rudiger is ‘Loco’ (Crazy), David Alaba is ‘Alabama’, Ferland Mendy is ‘General’, Eduardo Camavinga is ‘Pantera’ (Panther), Federico Valverde is ‘Halcon’ (Hawk), ‘Gaucho’ (the cowboy-like horsemen who are a folk symbol in his native Uruguay) or ‘Bombazo’ (Bombshell — because of the power of his shots), while Arda Guler is ‘Abi’ (‘older brother’ in the language of his Turkish homeland). Players use these nicknames regularly on social media, evidence of the positive atmosphere in the dressing room.

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That was helped last term by the mix of youngsters and veterans such as Nacho, Kroos and Joselu — all of whom have left the club this summer. But other experienced players such as the 38-year-old Modric and Lucas Vazquez, 33, remain after they extended their deals for a further year.

Club staff have played an important role in forging that harmony.

Last summer, the influential chief scout Juni Calafat took new arrivals Bellingham and Guler and Brahim Diaz (who was returning from a three-year loan at AC Milan) for dinner at a well-known restaurant in the centre of Madrid. Guler then hosted a barbecue at his home after the crucial La Liga win against Barcelona in April, attended by Brahim, Valverde and staff members.

The players have a great connection with Ancelotti and the other coaches. Carlo’s son and assistant Davide is the key given that, at 35, he is closer in age to the players and speaks several languages.

Carlo and Davide Ancelotti have a good relationship with the players (Charlotte Wilson/Offside/Offside via Getty Images)

They also enjoy a good relationship with doctors, physiotherapists and trainers. That was clear when physiotherapist Jaime Salom insisted on being at the Bernabeu for Militao’s comeback from a serious knee injury against Athletic Bilbao in March, despite the death of his mother that week. Rodrygo dedicated a goal in that game to Salom.

“These kinds of details are usually given privately and often you can’t see them, but they are very important,” a Valdebebas source said at the time.

It all paints a picture of a united dressing room, ready to welcome another star player in Mbappe.

(Top photos: Getty Images)