Football is full of different characters but there are perhaps none who have a split personality quite like José Mourinho, as I can testify from personal experience. The mind goes back to the 2014-15 season, when Chelsea won the Premier League title during Mourinho’s second spell there. I had just written a column for the BBC praising José for bringing a spark back to the club and, as our paths crossed at the training ground at Cobham, he gave me a big hug and thanked me for the kind words. There was a smile on the manager’s face and a twinkle in his eye. Fast forward to the following season and around the time the Eva Carneiro affair was taking hold. Once again José and I crossed paths at Cobham; he was leaving the media room as I was entering it to do some media for Chelsea TV. “Hi boss,” I said as we met. Mourinho practically blanked me. No words this time, no pleasantries, and the type of look that screamed: “What are you doing here?” In my view, when things are going well for José and people are saying nice things about him he becomes the most likable guy in the room. But when the pressure is on and things are starting to go badly a completely different person comes across – an edge takes over and, as we are seeing currently, he resorts to reminding everyone of his past success in a bid to deflect from current failures. Or perhaps, to put it more accurately, to remind everyone how great he once was. Mourinho in this moment seems insecure and during his time as a manager that insecurity has led to some real Jekyll and Hyde behavior. Now it’s the turn of those at Manchester United to experience it. It can be entertaining but also damaging, for Mourinho as much as anybody because by constantly banging on about what he achieved in the past he is bringing into sharp focus the fact he is not doing it now. Imagine if every time Manchester City lost a game Pep Guardiola went on about what he won at Barcelona? It would get very tedious very quickly, and that is what is happening with Mourinho at United. Saying that, I think the club should stick with him and Mourinho can show, for perhaps the first time in his career, he is the type of manager who can withstand a stormy period. The next few weeks are going to be interesting, especially if the pressure around the manager does not subside. That can happen in two ways – if the team keep winning and he calms down. For United’s sake, both of those things need to take place as quickly as possible. Thinking back to how it fell apart for Mourinho at Chelsea, I do have some sympathy for him. At most clubs it is the manager who determines the long-term stability of the players but at Chelsea it seems very much the other way round. On the whole the players are good guys - humble, keen to succeed – but they are also sensitive to managerial styles and when one gets stale, or simply no longer suits, there develops a real agitation for change. Take, for example, the way Eden Hazard told Mourinho he was injured and had to come off in the defeat at Leicester in December 2015 that led to the manager being sacked, or the way the same player made clear last season he was not happy with Antonio Conte deploying him as a striker against Manchester City. The big players historically hold a lot of influence at Chelsea and while I would never doubt their attempts to win matches for the club, their levels undoubtedly change depending on how they feel about a manager at the time. They’re either having him or they’re not, and once they’re not it spells borrowed time for the guy in charge. That’s why I’m reluctant to form firm conclusions on how successful Maurizio Sarri will be at Chelsea. He’s had a great start, with four wins in four games, and there are clear signs of him imposing his fantastic, forward-brand of football at the club, but in part it’s working because the likes of Hazard and David Luiz are buying into what he is trying to do. They had problems with Conte and have now decided, with a new man and a new way of playing, to go again. How long that will last is hard to say. Being a former Chelsea player I wish them all the best for the season. On a broader level I hope someone provides Manchester City with a fight for the title. Frankly, it was embarrassing to see how much better they were compared with the other teams in the division last year. Liverpool were the only club to ruffle City’s feathers last season, and have started this one well, so I can definitely see them challenging for the title. Their front three were phenomenal for last parts of last season and it will be interesting to see whether Mohamed Salah can go again and reproduce 30-plus goals. I’d also like to see Tottenham be serious contenders but I have my doubts they can be. Spurs have an amazing team, a world-class striker in Harry Kane and an amazing manager, but they appear to be a club associated with winning games but never winning any trophies. Regardless, I’ll be watching on with interest from Turin, where I’m continuing to adjust to a new life in a new city. The experience has so far been great. Turin is as Italian as it can get but the language continues to be a challenge. Picking up words is one thing but constructing sentences is a whole other difficulty. But I’m determined to improve and fully embrace this new chapter in my life. It’s great being part of Juventus. As expected, there’s a real family feel to the club, alongside a big desire to win as often as possible. I feel very much at home, having developed a good camaraderie with my teammates already. Training is also fascinating – I’m learning things on a technical level that I have never learned before. Aged 31, I feel like a kid again. Unfortunately, I am yet to bump into Cristiano Ronaldo. Saying that, I have seen Cristiano Jr, his son, who plays for the youth team. They train at Vinovo, where we train, so … you never know.The Guardian Sport