Rafa Nadal's coach Carlos Moya believes Roger Federer and Novak Djokovic are Rafa's biggest threats in this year's US Open.
"Djokovic is close to his best level and Federer is still a candidate for the most important titles," he said.
Nadal had to battle hard to get through his round of 16 clash against Nikoloz Basilashvili. His quarter-final opponent is Dominic Thiem.