The world number one Rafael Nadal and three time champion had to retire during his semi – final match at the US Open due to a knee injury against Juan Martin del Potro. Nadal retired at the end of the second set with Del Potro leading 7-6 6-2. In the final on Sunday Del Potro will face Novak Djokovic who won his semi-final in straight sets out classing Kei Nishikori from Japan 6-3 6-4 6-2. Djokovic will be aiming to equal Pete Sampras tally of 14 Grand Slam titles.