"I cannot support him even more than I am doing," the Spain midfielder said. "I am always saying he deserves it, 100 per cent.
"We are not playing well but that does not mean we are not in favour of the manager or something like that. We want to win for Chelsea.
"We want the club to be at the top and [with] someone like Mourinho who is having difficult times and the players, then you have to support each other and give your best.
"It has been really difficult. For me, the manager and some other players, we have always been lucky enough to play for big teams. Always trying to get to the top and always be fighting for things.
"In the Champions League, we are still there. The FA Cup has not even started yet so it is all about the league, trying to be as high as we can around Christmas because then it will be a very, very tough time."
Fabregas believes luck cannot be used as an explanation for the slide in standards.
"When you know things are not going your way, you have to do even more. When things go well, you touch the ball with any part of your body. You are not looking, and it goes in.
"Unfortunately, the ball does not want to go in at the moment."
Fabregas also stressed how important it could be for Chelsea if Diego Costa started scoring more regularly.
"The striker is the most important player on the pitch. You can play well, defend well, but it is about scoring goals, about scoring one more goal."