Andy Murray to meet Rafael Nadal in US semis

Andy Murray overcame Argentina's Juan Martin del Potro in four sets to reach the US Open semi-finals, where he will play world number one Rafael Nadal.

The British number one produced some wonderful shots but had trouble closing out a tight match before winning 7-6 (7-2) 7-6 (7-1) 4-6 7-5.

In his first Grand Slam semi-final 21-year-old Murray is to meet Nadal, who outclassed America's Mardy Fish.

Nadal suffered an early scare before coming through 3-6 6-1 6-4 6-2.

Bidding to become the fifth man to win three Grand Slams in a year and contesting his first US Open semi-final, Nadal is likely encounter tougher opposition in the form of Murray however.

The Scot, facing Del Potro for the first time since he accused the teenager of insulting his mother Judy during a Masters Series match in May, got the upper hand when he broke serve in game two.

But after going 4-1 up he saw Del Potro power back to win the next four games and serve for the opening set.

Murray produced a glorious winner to break the Argentinean's serve and then dominated the tie-break to win the opener.

The second set went with serve until Murray broke at 5-5 to serve for the set, only to then throw away the opportunity when Del Potro broke to love.

It was an uncharacteristically lacklustre game from the Scot but he rallied magnificently in the tie-break to take a commanding hold on the match.

With Del Potro appearing nervous, irritable and lost for ideas, Murray broke for a 3-1 lead in the third set and looked to have one foot in the last four.

But Del Potro showed character to break straight back and, after needing treatment on his knee injury, powered his way to three straight games and the set.

When Murray dropped his serve in the opening game of the fourth set it looked like the ascendancy was with Del Potro, who looked to have shaken off his knee problem.

The match again swung, though, with Murray breaking back and then surviving a nervous service game to go 3-2 up.

Both players showed signs of nerves, mixing unforced errors with top-class winners, and they exchanged breaks once more.

Murray kept up the pressure and forced Del Potro to serve for the match, which he failed to do and sent a backhand wide to confirm his fate and seal Murray's passage into the semi-finals.

There he will take on Nadal in a repeat of their Wimbledon quarter-final.

On that occasion Nadal swept Murray aside in straight sets and, although the 22-year-old has since usurped Roger Federer as world number one, Murray's recent form would point to a close encounter.

Nadal went into this quarter-final having never lost a set in four meetings with Fish but that record would soon change as the American raced into a 3-0 lead.

Backed by a partisan home crowd on Arthur Ashe Stadium, Fish carried out his promise of coming into the net whenever possible and taking the game to Nadal.

But Nadal did not take kindly to losing the first set and, with two breaks of serve, raced through the second in 36 minutes.

Fish showed flurries of brilliance in the third but he could not cope with the ferocity of Nadal's groundstrokes and, when he came in to attack, he tended to be passed as the Spaniard found his finest touch.

With the match passing 0200 local time, Nadal was keen to bring it to a close and in the seventh game of the fourth set he broke Fish to go 5-2 ahead.

He then closed out the match comfortably to secure a place in the last four.