He told the club's website: "When I first came to City, a fan came to me and said: 'Don't worry about Europe, don't worry about where you are in the league, just beat Manchester United - twice!'
"So that's done at least. Now we are happy and that's very, very good.
"I don't know if we deserved to win the first one, we were a little bit lucky, but on Sunday we absolutely deserved it."
When asked what the trick was to beating United, he replied: "There's no trick - it's just to work hard.
"You know when you meet teams like this you have to have legs and track them down and not let them play football.
"If you let Fabregas from last week and Ronaldo have the football they are too good. You have to be aggressive and keep the team very compact. I think that is the secret, but that is a secret, okay?"