Wenger said: "Without a doubt, this year will be the most exciting year in the Premier League. After 16 games, there has never been four teams as tight as this.
"Manchester United have a chance because they have the individuals and potential to score goals at any moment.
"So, it is difficult to make a judgment between the contenders."
Looking at tomorrow's clash against Chelsea, he added: "Any of the top teams could drop points and we could still be in a strong position. We have played eight away and eight at home and we have done well. Sunday is not a decisive game.
"It is super-healthy to have four clubs challenging. What you want is that it is fair in the season. It can get out of hand if it is very tight.
"A football game has to remain a football game. We have a responsibility in that as well. But we have other responsibilities too, like playing good football."