Walcott insists the only way of overhauling United is by focusing on their own form.
"It's all about the consistency," he told the Official Arsenal Matchday Programme.
"We can't worry about United - we just need to win our games to stay in with a shout. The game against them here [at Emirates Stadium] will be a big occasion, I think, and it could come down to that.
"We'll just keep plugging away, trying to get those three points every week and exerting as much pressure on them as possible."