While fans of Chelsea have welcomed back their old boss, they're also expecting him to deliver from the very first day - which is quite a heavy burden to put on the shoulders of a single person.
We take a look at some of the most important challenges that await the 'Special One' in his second coming at Stamford Bridge:
Dealing with ageing club legends:
Nobody's guaranteed a place in the starting line-up when under the leadership of Mourinho, with the prime example being Iker Casillas at Real Madrid. A talent rising up from the club's own ranks eventually becoming a legend, only to be benched by the Portuguese.
Despite being aimed at Casillas, this description goes for John Terry as well. The 32-year-old Englishman found himself on the bench on several occasions under Rafa Benitez and has to prove himself to Mourinho, too, who yesterday said he would offer no favours to the players he managed in his first reign.
Apart from Terry, Mourinho will have to deal with another club legend, Frank Lampard, who signed a one-year extension just after the club's Europa League victory.
Staying on the good side of club owner Roman Abramovich:
The relationship between Mourinho and Abramovich wasn't all that good during the first reign of the Portuguese (even if they will tell us different).
In fact, it's widely believed that the tension between the two was the main reason for Mourinho's departure from London in 2007, but now the relationship between the two has bettered, says former Chelsea player and current assistant manager, Ray Wilkins.
The Blues fans will be hoping that things will stay this way and that their returned hero will be able to cope better with the fact that the Russian oil magnate will be constantly breathing down his neck, which is something Mourinho will have to live with if he wants to be successful at Chelsea.
Pleasing the fans:
Although still a Blues favourite, José Mourinho will have to work harder than he did at Real Madrid to stand high in the supporters favour.
Apart from his benching of Iker Casillas, his attitude towards the fans of Los Blancos is regarded a key factor in his increasing unpopularity at the Santiago Bernabéu, and if he wants to keep his place in the hearts of the fans of Chelsea, he really has to improve this part of his attitude.
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