US Open 2011: Rafael Nadal beats Andy Roddick to reach semis

Nadal is through to the semi-finals for the fourth successive year

Rafael Nadal kept his US Open title defence on track with a 6-2 6-1 6-3 demolition of Andy Roddick to set up a semi-final against Andy Murray.

The world number two raced to a 4-0 lead in the first set and never looked back, breaking three times in the second and once in the third.

Roddick was treated for a leg injury but looked lost for ideas as Nadal beat him in an hour and 53 minutes.

The Spaniard goes on to play Murray after the Briton overcame John Isner.

While Roddick appeared to be struggling physically in the latter stages, it was a highly impressive display from Nadal.

The 10-time Grand Slam champion hit 35 winners, including 22 off his fearsome forehand side, and he remains the only men's player yet to lose a set in the tournament.

"The beginning was really important," said Nadal. "Andy had a really tough match yesterday [against David Ferrer] so he was probably tired.

"I'm sorry for him - he has had a fantastic career and it a great champion."

Looking ahead to his meeting with Murray, Nadal added: "It's always a pleasure to play Andy, he's one of the players with the most talent on the tour.

"It's always exciting against him and a big challenge for me. I lost to him in the 2008 semi-finals and I will have to play aggressive, play my best tennis.

"If I play like I did today then I'll give myself a good chance."