United travel to the Etihad Stadium on Sunday for the first Manchester derby of the season in a game that will see the sides who have finished first and second in the Premier League for the last two campaigns go head-to-head.
The Old Trafford outfit regained the title from City last term, and Sunday’s game represents an early opportunity for the clubs' new managers - David Moyes and Manuel Pellegrini - to lay down a marker of their credentials this time around.
But United forward Rooney still believes matches against their historically fiercest rivals Liverpool mean more, despite the fact City have now established themselves as a major force.
"They're all big games. Obviously United and Liverpool has been a massive game over the years," the 27-year-old said.
"City have had their success recently, but I would probably say that United and Liverpool is still the biggest game."
Rooney has started the new campaign in fine form after an unsettled close-season during which he was heavily linked with a move to Chelsea.
And United boss Moyes has praised the England international's attitude and application in getting back to top form after a dip towards the end of last term.
"He's got a bit of that old toughness back … it's Wayne Rooney who's got himself in a real good physical condition, as I talked about in pre-season," said the Scot.
"Mentally we needed to see a Wayne Rooney who was aggressive and all-action, which he was capable of being.
"He was different: he could score, he could fight, he could work for the team.
"He had all those attributes in his game and I think recently everyone's beginning to see all those attributes come back."
