More than just a three hour, 31 minute marathon, the quarter-final was a test of survival played in suffocating humidity so extreme that officials called a halt to junior matches on the outside courts for more than two hours.

Play carried on at the Arthur Ashe but with temperatures nudging 100 degrees Fahrenheit (37.7°C) the stadium was turned into a sauna, leaving two of the sport’s true heavyweights, 6’10” (208.28 cm) American Isner and 6’6” (198.12 cm) Argentine Del Potro, suffering in the brutal conditions.

Anyone looking for serve and volley tennis came to the wrong place as the pair loaded up and traded bombs from the baseline, the American laying down 26 aces and Del Potro 14.

As expected with two big servers break chances were few and far between, Isner managing just three in the entire match and unable to convert any, while Del Potro had 11 opportunities cashing in on three, including one to close out the match.

It was enough to see Del Potro, the 2009 US Open champion, through to the last four at Flushing Meadows for a third time where he will face either top seed Rafa Nadal or Austrian ninth seed Dominic Thiem, who were playing later on Tuesday.

The Argentine had the sole break chance in the opening set but the third seed could not convert, while Isner had a mini-break at 3-3 in the tiebreak and turned that into a 1-0 lead.

That was the first set surrendered by Del Potro at the US Open this year and a positive omen for 11th seed Isner, who was 24-2 at Flushing Meadows when winning the first set.

With Isner drenched in sweat and showing signs of early distress, Del Potro pounced to secure the only break of the second set at 3-1 and that was enough to level the contest.

The third was a replay of the first with neither man able to break, sending the set to a tiebreak won 7-4 by the Argentine.

A 10 minute heat break did little to re-energise Isner as Del Potro broke the American at the first opportunity on the way to a 3-0 lead and then again to close out the contest.