Mourinho's side go into the clash at the Etihad Stadium three points off City - who top the table going into the weekend on the back of Wednesday's 5-1 crushing of Tottenham at White Hart Lane.
City have won 18 of their last 20 games in all competitions - drawing the other two - but Mourinho believes favourable refereeing decisions have helped them along the way.
He said: "I think they have everything. Everything.
"The players are obviously very good. Even with very good players, if the manager is not good, you don't do it.
"On top of that – and I want to make it very clear that, for me, it's just a coincidence and nothing else – the reality is they have many crucial decisions in their favour.
"They are lucky. Against Liverpool, the Sterling 'goal'. The penalty on Suarez. Against Newcastle, the goal that is a clear goal.
"Against Tottenham, Dawson's goal, the penalty and the red card.
"They are having everything. I repeat: just pure coincidence. But at the moment they have everything in their favour."
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