Nadal and Murray through to U.S. Open semis

By Julian Linden

NEW YORK (Reuters) - Rafa Nadal and Andy Murray joined Novak Djokovic and Roger Federer in the semi-finals of the U.S. Open after thrashing their American opponents at Flushing Meadows on Friday.

The Spaniard may have been struggling with his form and confidence for the past few months but the defending champion showed that he has lost none of his ruthless ambition.

Murray was less convincing against Isner but the towering American provided a much stiffer test than his countryman.

He took a set off Murray and pushed the fourth to a tiebreak only to find someone who has able to blunt his devastating serve and the Scotsman won 7-5 6-4 3-6 7-6.

"When he's serving you have no option other than to just try and get yourself in the rallies," Murray said. "You're under a lot of pressure on your own service games, so you don't want to just be rash and start trying to make huge winners or do anything stupid."

There will be little time for Nadal and Murray to celebrate their wins with the pair due back on center court on Saturday afternoon for their semi-final.

"It's always a pleasure to play against Andy," Nadal said. "The matches against him are always exciting, so it will be a big challenge for me."

Federer and Djokovic also meet Saturday and the winner of each men's semis will enjoy a day off as tournament organizers moved the final from Sunday to Monday after two days of play were washed out.

The rescheduling has also affected the women's draw. The final, normally played on Saturday night, has been moved to Sunday, the 10th anniversary of the September 11 attacks, while both semi-finals will be played on Saturday.

With four semi-final matches scheduled for the same day, tournament officials have taken the unusual step of scheduling one of them on a much smaller showcourt.

The semi-final between Australia's Sam Stosur and unseeded German Angelique Kerber will be played on the Grandstand as Louis Armstrong Stadium was still not suitable for play after the heavy rain during the week.

(Editing by Frank Pingue)