Magic Murray in dreamland as he breaks new ground

JUST ten days in New York and four hours on the Arthur Ashe Stadium have changed Andy Murray's world forever.

The Scot beat Juan Martin Del Potro 7-6 (7-2), 7-6 (7-1), 4-6, 7-5 last night to reach the first grand slam semi-final of his career. And by winning the match, he ensured that his ranking will be up to No4 when the new world order is published on Monday. Murray is now living with the big boys, the very best of the best.

There is every possibility that he will face Rafael Nadal on Saturday, one of only three men in the world who are better at playing tennis than Murray. Those are the sort of matches Murray has dreamed of playing since he was a boy.

Playing Del Potro, a teenager from Argentina, may not have been the highest-profile match of the whole tournament, but it was a massive moment for Murray. This match was his ticket to the top.

It was not a match that he will remember with affection and the third set is one which he would rather forget, but the very fact came through it will fill him with enormous pride.

For the first few games, Murray seemed not to have broken step from Monday night when he pummelled Stanislas Wawrinka in the previous round. Back on his favourite court, still wearing his favourite grey shirt, he had taken the first set by the scruff of the neck within a matter of minutes.

Del Potro had warned before the match that their match in Rome, the bad-tempered affair that almost had the two men exchanging insults, meant nothing. Playing down the bad blood between him and the Scot, he wanted a quiet day at the office and pointed out that this was a different day, a different surface and a different situation.

What Del Potro omitted to mention was this was a different Murray, too.

He came with a simple yet effective gameplan – starve the big man of pace and wait for the mistakes to rack up. It worked like a dream as Murray sprinted to a 3-0 lead, slicing his backhand, looping his forehand and leaving the Argentine to try and whip up some fizz and bite on his shots. More often than not they ended up in the net.

Murray was also dragging Del Potro into the net with drop shots and then lobbing him to send him racing back again. At 6ft 6in tall, movement is not the strongest suit in the Argentine's game but, even so, lobbing anyone of that height takes some doing yet Murray did it to perfection.

But then Murray changed tack. Instead of infuriating Del Potro with guile and nous, he started playing the Argentine at his own game. Putting more muscle behind his shots, he gave his opponent the pace he craved and was gradually pushed further and further back as Del Porto started slapping his forehand and knocking the cover off the ball.

Only when Del Potro came to serve for the set did the nerves kick in and as the big man became more tentative, so Murray dragged him into a long and patient rally on break point and forced him into the error. Once into the tie-break, the Scot was soon in charge and with a drop shot that dropped over the net and landed gently beyond the Argentine's flapping racket, he took the lead and never let it go.

Del Potro came to the quarter-final on a 23-match winning run that stretched back to just after Wimbledon. The 19-year-old has played a lot of tennis this summer and by the end of the first set, the effort had taken his toll and he needed treatment for a knee problem. But still he would not slow down or give up.

By the second set, the Scot had taken his courage and his chances in both hands. Playing from the first row of the stands was not going to get him into the semi finals and even if in pushing forward he ran the risk of getting overwhelmed by the occasional flashing winner from Del Potro, he was in a position to bully his man and control the point if his chance came.

He may have made a hash of serving for the set – offering up his service game with four unforced errors – but he went for the jugular in the tie-break, conceding just one point as he took a two-set lead.

But that was when Murray's nerves got the better of him. The nearer he got to the finish line, the tighter he got and from being 3-1 up in the third set, he dropped serve twice to lose the third set and was quickly a break down in the fourth.

There was no let-up from Del Potro and when he achieved three more break points at 3-3, the Scot could not hold out.

But at just the wrong moment for the teenager, a few errors crept back into his game and – coupled with one brilliant retrieval from Murray – the sixth seed broke straight back.

In a turnaround as dramatic as the one Del Potro had mustered in the third set, Murray was now back on top and won his service game to love to move to the brink of victory.

But if he had hoped his opponent would crumble he was to be disappointed, the Argentine seemingly nerveless as he levelled easily. Serving to stay in the match a second time proved a different story, however, as errors from Del Potro gave Murray two match points – and when the Argentine put a backhand wide three hours and 58 minutes of great drama was over, and the Scot screamed his delight into the New York sky.

Meanwhile, Roger Federer scraped into the quarter-finals late on Tuesday, yet his fist-pumping celebration of a five-set win over a relatively modest opponent did as much to demonstrate the Swiss' perceived vulnerability as his title threat. The former world No1 beat Russia's Igor Andreev 6-7 (5-7), 7-6 (7-5), 6-3, 3-6, 6-3, and the normally even-tempered Federer celebrated with an enthusiasm that he rarely exhibited even in his 12 grand-slam title wins.

Federer's opponent in the quarters will be Luxembourg's Gilles Muller, who pulled off a big upset by ousting Russian No5 seed Nikolay Davydenko 6-4, 4-6, 6-3, 7-6 (12-10).

Novak Djokovic, the third-seeded Serb, struggled to a five-set win over Tommy Robredo, beating the Spaniard 4-6, 6-2, 6-3, 5-7, 6-3 to set up a quarter-final clash with American Andy Roddick. The eighth seed routed Chile's Fernando Gonzalez 6-2, 6-4, 6-1.

• Watch a slideshow of pictures from the match here

Watch an interview with Andy Murray here