"I don't have the shape to do that but maybe if I'm still working and still going in the same way, maybe in the future I can."
With the men's game currently enjoying a purple patch in terms of both quality and competition, the 6ft 6in Argentine cannot afford to stand still.
But history suggests players who win Grand Slam titles in their early 20s, and before fully developing or reaching their peak, tend to materialise into serial champions.
Del Potro is soon to turn 21 and has a game for all surfaces, with a booming serve, laser-guided groundstrokes, a vastly-improved volley and majestic movement.
Provided he keeps injury free, controls his emotions and contains his occasionally-volatile temperament, the top four of Federer, Rafael Nadal, Andy Murray and Novak Djokovic had better watch their backs.
"Rafa and I have had some epic ones over the years," said Federer. "Who knows, maybe Del Potro is going to join this as well."
Del Potro hails from Tandil - a modest rural city of 100,000 inhabitants, located 250km south of Buenos Aires - where he began playing tennis at the age of six.
Del Potro hails 'unbelievable' win
He learned his trade at Club Independiente under the stewardship of coach Marcelo Gomez, who also trained Tandil natives Mariano Zabaleta, Diego Junqueira, Maximo Gonzalez and Juan Monaco.
"Juan Martin has just made history in Argentine tennis," said an emotional Gomez, who watched the final on a big screen at Club Independiente.
"At the age of 20, he beats number one ranked Federer to win the US Open. I don't think he understands the magnitude of what he's just accomplished.
"We have a work method in Tandil. People here celebrated in the streets as if we had just won the soccer World Cup."
From an early age and throughout his rise up the junior and senior rankings, it was evident that Del Potro had the ability to go far - especially on hard courts, which have played host to five of his seven ATP Tour titles.
He claimed the prestigious Orange Bowl at the age of 14 and really came to prominence in 2008 by winning 23 matches and four tournaments in a row after Wimbledon.
Del Potro struggled to digest the magnitude of his triumph
Del Potro was reduced to tears after that sequence was ended by Murray in the US Open quarter-finals and was also involved in a heated exchange with the British number one at the Italian Open earlier that year.
The South American, known as the Giant of the Pampas, seemed to have matured in time for the 2009 season and served further notice of his capabilities by beating Nadal in Miami, taking Federer to five sets in the French Open semi-finals and thrashing Nadal in the last four at Flushing Meadows.
But, as Murray knows only too well, winning that first Grand Slam title is easier said than done. The last 24 Grand Slam tournaments have been shared by just five different players.
"He has the personality, ambition and potential to get to the top of the world rankings," said Nadal's uncle and coach Toni. "He had an amazing year in 2008, so we knew he would turn into a dangerous rival."
As a boy, Del Potro actually preferred football to tennis - "when I was young I played soccer better than tennis, I don't know what I am doing here," said the Boca Juniors fan after beating Federer - but there is no doubting where his focus now lies.
His superb run in 2008 made him the first player in ATP history to win his first four titles in as many tournaments and the 12th teenager to win at least four titles in a season.
Ten of the previous 11 went on to reach number one in the world, and it looks like Del Potro could follow suit.
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