As the feel-good story that is Juan Martin del Potro continues at the US Open, the Olympic Games silver medallist admitted he has exceeded his own expectations.

Del Potro's return to the scene of his greatest triumph - US Open glory in 2009 - for the first time in three years will roll into a second week after Saturday's 7-6 (7-3) 6-2 6-3 third-round victory over David Ferrer.

The popular Argentine tennis player arrived in New York on the back of a run to the final of the men's tournament at Rio 2016, form which has surprised Del Potro himself following years of injury problems.

"I didn't expect to be in the second week of this tournament. I didn't expect to get a medal in Rio. I didn't expect to play at this level in this part of the year," Del Potro told reporters.

"Of course, I just want to be free with my wrist, trying to play in a good level as I did couple of years ago. But I think I'm surprised with my level at the moment. I'm surprising the guys on tour, my colleagues.

"I can be dangerous in the future once again," he added.

"The best players on tour are talking good things about me. That's important to myself, to get confidence with my level, with my play, with my game.

"If they see something good in my game, that's important, because I'm showing a good game at the moment. If I see my way to the future will be better, even better than today, and that's important."