The Argentine defeated his opponent 6-4 6-0 in Montreal to set up a second round encounter against Marin Cilic.
"My serve is very important for my game and today it went really well, especially in the second set," said the world number 19.
"At the beginning of the match I was a little confused with the court and the balls. It was difficult to control the match.
"But in the second set my game improved and I played alot better."
Del Potro is the same side of the draw as Novak Djokovic and could meet the world number one in the quarter-final of the competition.