Rooney hopes to put the heartache of losing the Barclays Premier League crown on the final day to rivals City behind him, but stopped short of saying Sir Alex Ferguson will reclaim the title this term.
He said: "I don't know. Obviously everyone has their opinions. Some people think City, some people think United, some people think Chelsea.
"I'm not really going to get into that but we're working hard to try to win the title back anyway so hopefully we can do that.
"Obviously it's (last season) not something you want to look back on, when we've won leagues in the past we've looked forward to the upcoming season and if we haven't won it then we've been looking forward to the season coming up.
"It's a big disappointment but we have to move on."