The Spaniard, who is currently recovering from a knee injury, described the US Open champion as a "very complete player" with a good all-round game.
"Andy's a very complete player all round. It's hard for me to speak about any specific area of his game which is particularly hard to face," ESPN quotes Nadal as saying.
"He basically has it all, a great serve, backhand, forehand, he's fast, and he's a fantastic player all round.
"In recent years he's become a bit more consistent which is something you find with time, and he's one of the best in the world."