US Open champion Juan Martin del Potro was greeted by thousands of fans and feted with rock band Queen's seminal "We are the Champions" when he made a triumphant return to his hometown of Tandil on Thursday.

An emotional Del Potro, who upset world number one Roger Federer in five sets, reached the town's main square on top of a fire truck waving to thousands of fans who turned the four kilometre ride along the city's streets into a carnival.

"I owe this to Tandil," he said from the balcony of the municipal palace after receiving the keys to the city where he played his first matches at the age of six.

"I don't want to cry but thank all of you -- the ones that were cold waiting on the streets, the ones that ran along the route just to greet me," said Del Potro, wrapped in an Argentine flag.

Tandil, a modest rural town of 100,000 has turned into the unlikely cradle for Argentine tennis with ATP players Mariano Zabaleta, Diego Junqueira, Maximo Gonzalez and Juan Monaco all hailing from the city 350 km south of Buenos Aires.

Del Potro, who will turn 21 next Wednesday, made a stop at the Club Independiente, where he started his career, while loudspeakers blared out Queen's rock anthem.

The US Open victory assured Del Potro of qualifying for the season-ending Masters tournament in London in November.