When Andy Murray’s surge of eye-catching form deserted him for an hour and a half at Flushing Meadows, there were very few present who thought they would be seeing the former title-holder in the third round. But when did the Scot ever let odds bother him?

In a monumental fightback on a day so hot that the young American Jack Sock collapsed on court and was carried semi-conscious and feet dragging to the comfort of the medical room Murray needed every ounce of his Caledonian grit to recover from two sets down and grind down the excellent challenge of the world No35, Andrea Mannarino.

It took him three hours and 17 minutes to win 5-7, 4-6, 6-1, 6-3, 6-1 on the tournament's main court, Arthur Ashe, where a partially finished roof filtered the light and blocked the wind but could do nothing about the heat. The temperature hit 93F in late afternoon, as players and spectators alike sweltered, conditions that were always going to test fortitude and patience as much as skill – and that was just in the stands.

Players have become accustomed to the appalling stewarding here, which allows fans to wander in, beers and hot dogs in hand, as if they were at home in their front room, but one attention-seeker got it badly wrong towards the end of the first set. As Mannarino went up to serve, our friend rose from his seat in the stands just behind the Frenchman’s serving arm and theatrically wiped his face with a large white towel, to predictable hoots of derision. There will have been some nearby citizens with suggestions of more effective ways to clean his clock.

Murray seemed more put out by these interruptions than Mannarino, who, unburdened by expectation, played with more freedom to take the first two sets. It looked decidedly grim for the former champion, who was particularly unsettled by what he perceived to be a poor line call late in the second set.

Nor was he delighted when Mannarino drilled him in the back with a well-struck, short-range volley in the fifth game of that set, one in which he double-faulted and had to fight through four deuce points before holding with an ace.

Mannarino, however, was playing superbly still. He held to love in four minutes and went on to serve out the set, wrapping it up with a gently tapped smash.

Murray looked spent. His box looked distraught. But he was far from done.

We might have known. He has done this so many times before, He roared back to take the third set in 31 minutes and Mannarino, who surely thought the upset was there for the taking, was stunned.

Murray signalled his further thirst for the fight by pulling off the rescue of the match, and maybe the tournament at the start of the fourth set, hunting down three balls that anyone else would have given up as a lost cause, to force a final loose shot out of Mannarino for deuce on the Frenchman’s serve.

Mannarino continued to torment Murray with drop shots – and held – but there was a sense that he was fading. When his weary left arm belted a fifth double fault into the net for a break in the third game, his resistance looked to be finally deserting him.

Mannarino served to stay in the set just before the three-hour mark but his super-fit opponent broke him to 15 and they went to a fifth set. This was alien territory for Mannarino, a comfort zone for Murray. When he served out to 15 with his 21st ace, he had pulled off his eighth career comeback from two sets down.

The next test of his extraordinary reserves will be the Brazilian Thomaz Bellucci, who beat Hoshihito Nishiokaof Japan 6-0, 6-3, 6-4, in exactly 100 minutes, one of the shorter matches in the first four days of the tournament. Were Murray to get through to the fourth round so quickly he would indeed be thankful, given the relative strolls experienced by his nearest rivals, Novak Djokovic and Roger Federer, who have hardly been stretched yet.

Murray’s strength was always durability but he will not want to waste too much of it in the first week and he knows that this was a struggle he might have avoided but for the arts and crafts of an opponent who lost not through lack of wit but a surfeit of energy.

(Guardian service)