The Blues endured an indifferent start to the season after the return of Mourinho, but after six victories in a row, Mikel has admitted that the club's former boss has brought back a winning mentality at Stamford Bridge.
The 26-year-old told Chelsea TV: "This game is all about winning and the manager that brought this transformation of winning to this club is back now. He still has the same idea of how he wants us to approach every game with a win, win mentality.
"He walks around the place full of energy, full of confidence, and really, he is not doing it for himself but for you to see how he goes about his business. He wants you to emulate that into yourself and start behaving in a similar way.
"This is because confidence can lead you to so many places that you never thought you could go and it is just brilliant to work with him again."
Mourinho won two Premier League titles, one FA Cup and one League Cup during his first spell at Chelsea.