Andy Murray overcame a number of physical problems to progress to the second round of the US Open with a 6-3 7-6 (8-6) 1-6 7-5 victory over Robin Haase.
The British No 1 struggled with cramps in his legs, arms and side at various point during a match held in rising tempuratures at Flushing Meadows' Louis Armstrong Stadium.
He made his way through the first two sets in comfortable fashion but began to feel the strain when Haase won nine straight games in the third and fourth sets.
Despite being clearly impaired Murray managed to hit back and clawed his way onto level terms before breaking at a timely interval at the end of the fourth set, allowing him to wrap up a dramatic win in three hours eight minutes. Murray will play German qualifier Matthias Bachinger in the next round.
"I don't know exactly what it was, whether it was the heat or not, but I was cramping after an hour and 45 minutes, which isn't normal," Murray told Sky Sports.
"I didn't really know what to do in that third set - my quads were cramping and then I started to get it in my lat (muscle), when I was throwing the ball up to serve, and then in my forearms.
"I didn't know what to do, whether to conserve energy or try and finish it in three sets. But then I got broken at the beginning of the set. I just tried to hang around and at the end I was just trying to play without using my legs much and I managed to get through."
There was no sign of the problems to come when Murray raced into a 4-0 lead at the start of the opening set, although he did concede one break of serve and saved another break point before being able to win the set.
It was Haase who made the better start to the second set, moving into a 3-1 lead as Murray's forehand started to go awry, but the 2012 champion hit straight back.
Murray missed a chance to break for 5-4 but held serve confidently enough to take the set into a tie-break, where he managed to get across the line despite seeing two set points go amiss at 6-4 up.
But the match suddenly became a struggle in the third set as the eighth seed, having won the opening game, promptly lost six in a row with his movement severely restricted.
With the temperature hot but not extreme Murray implored the umpire to call for ice and he came out for the fourth set with the clear intention of trying to make the rallies as short as possible.
It did not work as Haase moved into a 3-0 lead before Murray, after finally being able to place some ice on his thigh, stopped the rot.
Haase then called for the trainer after the fifth game for treatment to his foot and was broken back following an aggressive return from Murray, who was dealing with cramp all the way down the right side of his body.
Murray did not sit down at the changeover in an attempt to keep the cramp at bay but he dropped serve once again to leave Haase serving to make it two sets all.
The Dutchman could not convert, however, handing Murray the break back with a double fault, and two games later the Brit put himself in position to serve for the match with a forehand winner.
Inevitably it was not straightforward, Murray having to save three break points before finally clinching the victory.