The Frenchman admitted that he is the underdog going into the match, and said that he is wary of his opponent's powerful forehand.
"I think it's very difficult to play against Rafa," BBC Sport quotes him as saying. "It's very difficult because he's powerful, especially with the forehand.
"I'm in the semis in the US Open. I want to do the best I can do. I will try to go in this match to win. If not, don't go on the court.
"But I know he's the favourite for the match. Nobody will say I'm the favourite."