Rooney scored the only goal of the game and his 100th for the club.
“It was a massive win,” Rooney told MUTV. “Not necessarily because it was against Manchester City, but because three points are vital, especially with Chelsea and Liverpool playing after us. We simply had to win and I thought we produced a good performance.
“To be honest, I didn’t really think about [the fact it was my 100th goal]. I was more excited about scoring away at City. And for it to turn out to be the winning goal is very pleasing.
“City took six points off us last season. The players, the fans and everyone at the club was hurt by that, so to pick up three points against them today was a very good result.”
