Tottenham have been a likable club for such a long time. From David Ginola to Christian Eriksen they have had gifted players and allowed them to play nice football, without winning very much. There have been two League Cups in the past 20 years: this is a team who have not trodden on many people’s toes. Outside Arsenal and Chelsea, and even then just for tribal reasons, nobody can really hate Spurs. I certainly like them a lot. This is not a bad image to have, but it is one that is about to change – because Tottenham have just decided to get ugly.

Once they fully adopt José Mourinho’s win-at-all-costs mentality there is going to be a big change in how the neutral perceives them. But first, their players are going to have to go through a huge mindset shift. They are going to change from being a squad of individuals whom everyone likes and respects, people such as Son Heung-min and Lucas Moura who play with a smile, to a team nobody particularly likes, led by a manager who deliberately antagonises his rivals.

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People are saying it’s not a Spursy appointment, and maybe that’s how it feels now. If it works how Daniel Levy clearly wants it to, by the time Mourinho leaves Spurs will have changed and could go from being the eternal bridesmaid to the bride, with what feels like a ruthless appointment being rewarded with trophies.

I spent six successful years as a player at Chelsea, and I have realised the extent of the winning outlook that became ingrained in me while I was there, playing under a manager – Emma Hayes – who would accept nothing less than winning. I know from my time at other clubs that not every player shares that outlook. I learned there is a difference between being at a club that is happy to come second, and representing one that will settle for nothing less than first – and the key difference lies inside the players.

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Mourinho will want to bring that culture into Tottenham, but there may be people who struggle with the transformation. There is always a shift when a new manager takes over, but I think what the Spurs squad is about to go through is another level: Mourinho will not just want to change the tactics and the lineup, he will want to change the entire culture of the dressing room.

With any managerial change, players decide pretty quickly how they feel about the new person in charge, and once that has happened it can be very difficult to change it. A certain number will always think to themselves: ‘I’m not having this guy.’ And the more the manager wants to change, the more likely it becomes that players will react badly. This is Mourinho’s first great test.

There will be some players at Tottenham who have that fire, and others who lack it. At this moment, it is hard to tell who they will be. Harry Kane is a hero to the Spurs fans, one of their own. His mentality, his pursuit of individual excellence, has always been outstanding, but he has spent his entire career at a club where the ambition is to come third or fourth and maybe win a cup.

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Dele Alli has worked himself up from MK Dons to the England team but has never experienced the pressure of feeling that victory is not just an ambition or an expectation, but a necessity – every week. How much does Kane want to win? How badly does Alli want a trophy? These are big questions, career-defining questions, and everyone in the Tottenham dressing room will have to deal with them over the coming weeks. Mourinho may need to overhaul the squad, but first he has to identify the individuals not just with the ability but with the inner strength and desire to take the club where it wants to be.

Levy has made an appointment that will also have an impact on him. He has overseen the construction of a spectacular, world-class stadium but if the team are not quite at the highest level it is at least in part because, as Mauricio Pochettino repeatedly suggested, their transfer dealings haven’t been good enough or ambitious enough. If he wants Spurs not just to challenge Manchester City and Liverpool but to be in with a chance of actually beating them, he’ll have to step up his financial game as well.

It is 11 months since Mourinho was sacked by Manchester United, and it would be stupid for him to try to manage at Tottenham the same way he did at Old Trafford. If he is smart, he is going to have a more humble, softer approach. Even 56-year-olds with a history of constant success and an ego to match learn and change over time. Having watched that United side disintegrate around him, having read countless comment pieces about how he can never last three years at any one club, and having sat by his phone for the best part of a year waiting for a killer job offer that didn’t come, he will have had to eat a bit of humble pie – and I’m not sure that is a dish he is very good at digesting. But he can also look back over the nearly 20 years that he has been in management and see that even in his least successful periods he has been more successful than Tottenham.

It is a given that he will be butting heads with a few players, but he has also been a fantastic man-manager in the past. Some of the greatest players in the world have said he is the man who got the best out of them. On the other hand, he has a habit of clashing with particularly high-profile players – Paul Pogba at Manchester United, Eden Hazard at Chelsea, Sergio Ramos and Iker Casillas at Real Madrid.

Surely, though, he is wise enough to know it would be stupid to come in with an iron fist. Clearly some of the players had tired of Pochettino, of his tactics, his training methods and his standoffish behaviour, but it is obvious others are mourning him. Mourinho will have to do some nimble emotional navigation in these early days, before he starts to wind up the pressure. Then it is down to the players.