Rafael Nadal returns to Andy Roddick. REUTERS/Jessica Rinaldi
Nadal, the only men's player yet to lose a set in the tournament, set the tone early by breaking the American in his first two service games to race to a 4-0 lead and going on to break Roddick six times in all in the one-hour 53-minute romp.
With the win, the second-seeded Spaniard advances to a last-four clash with fourth-seeded Andy Murray of Britain, a 7-5 6-4 3-6 7-6 winner against American John Isner.
The other semi-final will pit top-seeded world number one Novak Djokovic of Serbia against 16-time grand slam winner Roger Federer, who owns five U.S. Open titles.
