Del Porto took the early initiative at Arthur Ashe Stadium, with the 24th seed claiming the opening set 7-5 against his Swiss opponent.

Federer was able to level the match in the second set 6-3, before the pair played a crucial and tightly fought third.

The set would be decided on a tie-break, which Del Porto edged 10-8 to put himself one step closer to the last four.

Del Potro would delight a crowd packed with his supporters by taking the fourth set 6-4 to end the challenge of Federer, who had been forced to come through two five-set matches early in the tournament.

It marks the first time Del Potro has reached the semi-final stage of the grand slam since he won the title in 2009, where he beat Federer in the final.

The Argentine, who has been dogged by wrist injuries in recent years, will face Spain’s Rafael Nadal as he seeks to add to his solitary grand slam success.

Nadal, the world number one, brushed aside the challenge of Russian teenager Andrey Rublev earlier in the day.

The Spaniard emerged as a 6-1, 6-2, 6-2 victor.

There is guaranteed success for the United States in the women's singles, with an all-American semi-final line-up confirmed today.

Coco Vandeweghe saw off the challenge of tournament top seed Karolina Pliskova in the first quarter-final of the day.

The American won the opening set on a tie-break, before going on to complete a 7-6, 6-3 victory over the Czech.

Vandeweghe will meet Madison Keys in the semi-finals, with the home favourite beating Estonia’s Kai Kanepi 6-3, 6-3.

Venus Williams and Sloane Stephens will compete in the other semi-final, with the duo having progressed to the last four yesterday.

It marks the first time since 1981 that there is an all-American semi-final line-up.