Patrice Evra claims Manchester United must spend as 'little time' as possible thinking about their neighbours City.
The sides meet in the eagerly-anticipated derby at Eastlands on Wednesday night but the United full-back believes the club's priorities are the Premier League and Champions League.
The France international does not see the fixture as any more important than games against Liverpool or Chelsea.
He told the News of the World: "Look, I like to win against Chelsea, I love to play against Manchester City and I hate to lose against Liverpool at Anfield. That's my mentality."
"They're always rivals, but every year we've got to win the Premier League.
"We don't think about Manchester City because they are not our problem."
The full-back also claims City are also-rans without skipper Carlos Tevez.
The Argentine, who joined the Eastlands giants last year when he moved from United, is expected to be fit for the big derby after suffering from a thigh injury.
And Evra said: "City have spent a lot of money, but for me Carlito is easily the best player they have.
"They have other good players, but he attacks and defends.
"They couldn't afford to lose him. He is a big player, the most important they have - and every single Manchester City player knows that.
"I am still very friendly with Carlos. We speak every day and he still comes to my house and I go to his, we are friends for life.
"Just because he went to City doesn't mean I cut my relationship with him."