Del Potro is the only man aside from Roger Federer, Andy Murray, Novak Djokovic or Rafael Nadal to win a Grand Slam in the last eight years, but believes that he should be considered an underdog to go all the way in Melbourne.
He told reporters: "[The big four] are so far from me at the moment. We play five sets and matches can be tough for all the players, so I am just thinking about my second round.
"Hopefully I can go far, but I need to play better and better. I know how tough it is to win a Grand Slam. But I also know the way to win a Grand Slam so I'm trying to do that for this year.
"But I think I played really aggressive today. I made a lot of winners with my forehand and served well. I made a very good start to this Open."
Del Potro continues his campaign with a second-round match against Benjamin Becker on Thursday.