The United striker believes City's Champions League exit, with the worst points score ever by an English club, reflects problems that have been camouflaged by the fact they have not lost a home Premier League match for two seasons.
"If we get three points there, it will be massive for us," said Rooney. "I think with City out of the Champions League, they are having a bit of a tough time and I think everyone can see that behind the scenes. If we can win, it will put more pressure on them.
"Obviously, it is a massive game, probably up there with Liverpool. The two of them. There is a big rivalry, the two of us are fighting for that No 1 spot. We're trying to go there and get three points. We are all excited for the game."