Drained Murray is forced to dig deep

It is an unusual way to find your best form, but when Andy Murray is around you always expect the unexpected. Just as he did in his thrilling fourth-round victory over Richard Gasquet at Wimbledon two months ago, the 21-year-old Scot went to the brink of defeat at the US Open last night before finally unlocking the talent that makes him one of the world's most exciting players.

Murray beat Austria's Jürgen Melzer 6-7 4-6 7-6 6-1 6-3 after three hours and 52 minutes of unrelenting drama. Having gone within two points of defeat at the end of the third set, he produced a thrilling fightback to win from two sets down for the third time, having also done so against Gasquet and in the Davis Cup against Israel's Andy Ram at Eastbourne two summers ago.

At the end, in a repeat of the gesture he made at Wimbledon, the Scot rolled up his right sleeve to flex his muscles. Once again, his much improved physical strength was a crucial factor in his victory. Playing such a demanding match on the airless Grandstand Court in heat and humidity may have taken much out of Murray, but his next opponent had a similar experience. Stanislas Wawrinka also had to come from two sets down to beat the Italian Flavio Cipolla after more than four hours.

Murray started his favourite Grand Slam tournament last week as one of the leading contenders. His first two victories had done nothing to alter that thinking, but for the first two hours of yesterday's match Murray looked decidedly flat. While Melzer hit some cracking ground strokes – he had 79 winners to Murray's 66 – the Austrian also made plenty of mistakes, making 71 unforced errors compared with the Scot's 29.

"I knew it was going to be tough to come back because he was playing really, really well," Murray said afterwards. "He was serving close to the lines and hitting the ball so hard and flat and very deep. He was taking a lot of risks and most of his shots were going in."

The first three sets featured plenty of good drop shots, which are usually Murray's trademark, but nearly all of them came from Melzer. Murray appeared to play too passively and it was only on his 10th break point that he broke Melzer's serve, in the fifth game of the third set.

Murray's return is usually one of his strengths, but he took an age to get to grips with Melzer's serve. Most right-handers have trouble against a left-hander, but Melzer's serve was nothing like as potent as Michael Llodra's in the previous round and Murray himself seemed puzzled by his inability to hit consistently damaging returns.

John Lloyd, Britain's Davis Cup captain, was watching in the stand and for long periods he must have had major concerns as he thought ahead to next month's World Group relegation play-off at Wimbledon against Austria, when Murray and Melzer will lock horns again.

Murray had the only break points of the first set, Melzer saving two in the sixth game and two more on set point at 5-6. The tie-break broke the pattern, however, with nine of the 12 points going against serve. Murray served at 4-3 but lost four of the next five points, twice beaten by drop shots. The Scot was furious with himself for letting the set slip away and it was a similar story in the second set. More break points went begging and at 4-5 the Scot played his worst service game. A snatched backhand into the net, a simple netted volley, another poor backhand and finally a misplaced volley handed Melzer his first break of serve and the second set.

As has happened so often in the past, adversity brought out the best in Murray. At 2-2 in the third set he finally broke serve with a rasping backhand return and let out a roar of celebration.

Murray being Murray, there was more drama to come as a dreadful drop shot allowed Melzer to break back and level the score at 5-5. Melzer went 5-4 up in the tie-break, but then missed a forehand and could do nothing as Murray created set point with a thunderous 138mph ace – the fastest of his career – and then hit a backhand winner down the line.

With Murray now suitably pumped up, the fourth set flew by and within half an hour the match was level. Melzer regularly sought treatment to his right calf in the final set before Murray broke for a 4-3 lead. At 3-5 Melzer saved two match points before Murray converted his third by drilling a forehand winner into the corner.

Asked to compare the victory with his Wimbledon win over Gasquet, Murray said: "They were both very good. I was in danger in both matches, but I felt like today Melzer was playing so well that it was going to be really tough for me to get back into the match. Gasquet was obviously playing great, too, but I still felt like I had a shot of getting back in there."

Rafael Nadal, who could meet Murray in the semi-finals, beat Serbia's Victor Troicki in straight sets, while the Williams sisters maintained their progress towards a potential meeting in the quarter-finals. Serena beat Japan's Ai Sugiyama 6-2 6-1, while Venus Williams beat Alona Bondarenko by the same score.