"The bad thing is when you win, next Tuesday you are like this another time," world number one Nadal added with a broad grin while pretending to throttle himself with one hand.

"You never know what's going on in two months, in five months, in seven months so it's very difficult to play during all the year at the same level, your best level.

"If I am playing at my best level, if Murray has a good day, he has a good chance to beat me or (Roger) Federer or [Novak] Djokovic or a lot of players. Every tournament is really tough."