Former champion Juan Martin Del Potro eased into the third round of the US Open with a 6-2 6-1 7-5 victory over fellow Argentinian Diego Junqueira.

Del Potro is playing in the tournament for the first time since winning the title in 2009 after missing last year with a wrist injury, and he is certainly someone the top seeds will want to avoid.

Junqueira is ranked 104th in the world and it quickly became clear he did not have the game to trouble Del Potro, who was powering his renowned groundstrokes into the corners.

The 18th seed was tested only in the third set, when Junqueira, who like Del Potro hails from the town of Tandil, managed to salvage some pride, but the result was never in doubt.

Wild card Julien Benneteau is also through to the third round after a 6-4 6-4 6-4 win over Denis Istomin. The Frenchman has carried on his good form from the ATP World Tour event in Winston Salem last week, where he reached the final.

Del Potro freely admits he is not yet back to the level than saw him beat Roger Federer in five sets in the final two years ago, but he feels he is on the right track.

The 22-year-old said: "I played better than my first round. I was more confident with my forehand, especially in the beginning of the match.

"It doesn't matter if you play good or not in the first round if you win. Now I'm in the third one, so I need to improve, I need to be more confident with my serves and forehands."

Del Potro, meanwhile, has no complaints with tournament organisers, who have so far overlooked him for the night sessions on Arthur Ashe Stadium.

He added: "They have (Roger) Federer, (Novak) Djokovic. I'm in the second part of the draw, so I play the same day as (Rafael) Nadal, (Andy) Murray, (Andy) Roddick, and they are fantastic players to play at night. So I think they are doing a good schedule."

Giant American John Isner, the man who beat Benneteau in Winston Salem, continued his good form, the 28th seed seeing off countryman Robby Ginepri 6-4 6-3 6-4 to make it seven straight wins.