Juan Martin del Potro reached the semi-finals for the third time in the last five grand slams after coming through a gruelling battle with John Isner. The two big men battered each other to near exhaustion in the humidity of Arthur Ashe Stadium but it was Del Potro who proved the stronger in a 6-7 (5/7) 6-3 7-6 (7/4) 6-2 victory that lasted three and a half hours. The popular Argentinian will now attempt to take a step he has not managed since winning his only grand slam title here nine years ago and reach another final. In among the wrist surgeries and long lay-offs, Del Potro has made three semi-finals, losing to Novak Djokovic at Wimbledon in 2013 and then Rafael Nadal here last year and at the French Open this summer. He then pushed Nadal all the way in a classic Wimbledon quarter-final and could well get another crack at the Spaniard, who was due to face Dominic Thiem in the night session on Tuesday. Del Potro said: "I'm so happy to reach another semi-final in my favourite tournament that's very special to me. "Of course beating John in this kind of match is like an epic. We both were tired in the end, we both fought until the end and I think I survived with my serve. That was the only difference I think." The extreme heat policy was again in effect and conditions were so hot at the start of the contest that all junior matches were suspended. The players took a 10-minute break at the end of the third set, and Del Potro said: "I lay down on the table and I didn't want to come back again because with this heat it's impossible to play tennis." Del Potro's cheer squad, a group of friends who have travelled from his home town of Tandil, were again a noisy presence, attracting the ire of Isner at one point in the third set. Del Potro now has two days off before the semi-finals but will be keeping to himself, saying: "If I met them it could be dangerous for me. We will have time to have fun together." Isner, who is having the best season of his career, was looking to reach his second consecutive slam semi-final and in doing so become the first American semi-finalist in the men's singles here since Andy Roddick in 2006. Many players have been driven to distraction by the small margins involved when playing Isner and one backhand that just drifted into the tramlines cost Del Potro the opening set - the first set he has lost all tournament. The Argentinian had only won three of his last seven meetings with Isner but gained the break he needed early in the second set and maintained his advantage. There were few of the thunderbolt forehands for which Del Potro is most famous, the third seed instead seemingly trying to conserve as much energy as possible. Both players had two chances to break in the third set, and the 15-40 chance that Isner missed at 2-1 ultimately proved to be his big opportunity. The American was not landing enough first serves to keep himself out of trouble, with Del Potro increasingly forcing him to play off his toes, and by the fourth set Isner's resistance had run out.<doc-sep>Last updated on .From the section Tennis Juan Martin del Potro was beaten by Rafael Nadal in last year's US Open semi-finals 2018 US Open Venue: Flushing Meadows, New York Dates: 27 August-9 September Coverage: Live radio coverage on BBC Radio 5 live sports extra; live text commentaries on the BBC Sport website Former champion Juan Martin del Potro reached the US Open semi-finals with a 6-7 (5-7) 6-3 7-6 (7-4) 6-2 win over John Isner on another gruelling day. The humidity was so stifling officials suspended junior matches on outside courts for more than two hours. Del Potro and Isner had a 10-minute break between the third and fourth sets as part of the extreme heat policy. Del Potro joked: "I had a shower, re-taped my ankles and laid down on the table. I didn't want to come back out." Isner said he got through 11 shirts and estimated he lost between eight and 10 pounds through sweating as temperatures approached 38C inside Arthur Ashe Stadium. "It's tough conditions out there, no doubt," said the American. "It's very humid. The air is pretty still for whatever reason. Maybe it's the roof structure." World number 11 Isner took the opening set on a tie-break before Del Potro levelled following a break in the fourth game of the second set. The Argentine world number three won the next tie-break and then broke in the second game of the fourth set en route to victory in three hours and 31 minutes. The 2009 champion will face top seed and world number one Rafael Nadal on Friday. The 29-year-old said his serves, which often matched Isner's for pace, were his biggest weapon on a physically punishing day. "I'm so happy to reach another semi-final in my favourite tournament that is very special to me," he said. "Beating John in these kind of matches - it's epic. We were both tired in the end and I survived with my serves during the match." Del Potro fights back The Argentine made the first big mistake of the match when he conceded a mini-break at 3-2 during the first set tie-break. Isner went on to take the set, but Del Potro bounced back as his opponent made an error on the second of three break points in the fourth game. Both players had two chances each to break serve in the third set which was eventually decided by another tie-break, which Del Potro won. The players decided to take the option of a 10-minute interval, but neither looked to have benefitted much on the resumption of play. The crucial break came in Isner's opening service game of the fourth as Del Potro delivered a flat double-handed backhand which was too good for the American. Del Potro sealed victory in the eighth game when Isner snatched at a shot near the net.<doc-sep>
Juan Martin del Potro made it through to the US Open semi-finals for the second successive year Former US Open champion Juan Martin del Potro overcame extreme heat and humidity in New York to defeat home hope John Isner and reach the semi-finals. The 2009 champion capped off the day session in soaring temperatures by ousting 11th-seeded Isner in a heavyweight slugfest of the towering big-servers 6-7 (5-7) 6-3 7-6 (7-4) 6-2. Del Potro, seeded third, dropped his first set of the tournament in an opening set tie-break, but rallied to make it eight wins in 12 meetings against Isner with another destructive display of power hitting. "I'm so happy to reach another semi-final in my favourite tournament that's very special to me," said Del Potro. "Of course beating John in this kind of match is like an epic. We both were tired in the end, we both fought until the end and I think I survived with my serve. That was the only difference I think." Isner, who was looking to become the first American man to reach the semi-finals since Andy Roddick in 2006, relied on his huge accurate serve as temperatures of 34 degrees Celsius and intense humidity on Arthur Ashe Stadium began to take its toll, although he did enough to send the third into a tie-break. Del Potro, who recorded a straight-sets victory over the 33-year-old in the fourth round of the French Open earlier this year, took control to take it and turn the match in his favour as both players invoked the 10-minute heat break rule before the start of the fourth. A wobbly Isner was suffering badly from fatigue in between points but was determined to put on a gutsy performance. John Isner suffered from the intense heat and humidity in New York But it was the giant Argentine who carried on from where he left off with a double break to see out the contest in style after three hours and 31 minutes as he marched into his third US Open semi-final. Del Potro will now face defending champion and No 1 seed Rafael Nadal for a place in Sunday's final. Nadal beat Del Potro in the semi-finals last year at Flushing Meadows, and again this year in the semi-finals of the French Open. We have every major tennis event covered from all angles via our website skysports.com/tennis. On the move? Head to our app for mobile devices and iPad, or follow our Twitter account @SkySportsTennis to join in the conversation. Tennis is back on Sky Sports screens with the Laver Cup in September while we will also have coverage of the ATP Finals in November with every match live on Sky Sports. But first, we will be across the final major of the year in New York as the US Open right through to the final with live blogs, reports, features and reaction.