Arsene Wenger's side are five points clear at the top of the table after 10 games and continued their strong start with a 1-0 victory over Borussia Dortmund in the UEFA Champions League on Wednesday.
However, Rooney warned Manchester United's next opponents that Arsenal need to maintain current form unlike in previous campaigns in order to end the club's eight-year wait for silverware.
"We'll have to wait and see where Arsenal are in March," he said.
"We have seen before that they have 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 to stay there and us to catch them."
United welcome Arsenal to Old Trafford on Sunday looking to extend their unbeaten run against Wenger's men to five games, with Rooney confident of getting all three points.
"We are obviously capable of beating Arsenal," he added. "We have done it many times in the past.
"They are on a good run of form and they are top of the league, so we know it's going to be a difficult game.
"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."
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