Andy Murray has set his sights on winning the US Open after his brother Jamie bowed out.

The Scot beat Juan Martin Del Potro 7-6 7-6 4-6 7-5 to reach the last four of a Grand Slam event for the first time in his career and set up a semi-final against world number one Rafael Nadal.

The Spaniard beat Mardy Fish of the United States 3-6 6-1 6-4 6-2 in their quarter-final and is favourite to win his third Grand Slam title of the year.

But Murray said: "When I watched the first night session of the tournament and saw all the winners of the US Open, I realised that winning is what really, really counts. I want to win."

Jamie Murray fell agonisingly short of taking the mixed doubles title at the tournament.

He and his American partner Liezel Huber lost 7-6 6-4 in the final to India's Leander Paes and Zimbabwe's Cara Black.

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