The Gunners meet United at Old Trafford on Sunday.
"We'll have to wait and see where Arsenal are in March," Rooney said.
"We've seen before that they've been in the top two until February or March and then faded away.
"They are doing brilliantly at the minute, so it's down to them to try and stay there and us to catch them."
"We're obviously capable of beating Arsenal," added Rooney.
"We've done it many times in the past.
"They're on a good run of form at the moment and they're top of the league, so we know it's going to be a difficult game.
"But we have to go into it with confidence and a belief this is when we can edge closer to them and bring us back into the mix of being at the top of the league.
"There are only nine or 10 games gone so there's no big worry at the moment. We're starting to do well. We're confident at the minute, we're getting more clean sheets and playing with freedom.
"If we can get the victory on Sunday then we're in a great position."
For breaking stories and all the great banter like us on Facebook: facebook.com/tribalfootball