Serena Williams’ coach Patrick Mouratoglou said he is surprised Rafael Nadal claimed that he is "weak" on court, telling L’Equipe he does not understand why the Spaniard made such a comment.

The former No. 1 has not been in top form this season, losing to Tomas Berdych at the Australian Open, falling to Milos Raonic at Indian Wells, and then losing to Fernando Verdasco in Miami. He played some clay events in South America, losing to Fabio Fognini at Rio and winning Buenos Areas over Juan Monaco. Now down to No. 5, Nadal has admitted to being nervous lately on court.

"There are two ways to approach a problem—deny it or recognize it, which is what he did. But this time he went further, and he did it publicly, and it's something that I had never seen before," Mouratoglou said. "Serena would never have done that. Nadal's team said over the years that Rafa is not good, and does not play well, his opponents are 10 times stronger. So for me what is happening is the continuation of this process. It could be a strategy, or a way to exorcise the pressure, but I could be wrong and maybe it's just a part of their personality to be so transparent."

Serena has won 19 Grand Slam singles titles, while Nadal has 14. The Frenchman also suggested that the comment could affect the way Nadal is perceived by opponents. "Rafael Nadal is one of the mentally stronger players, and to say that now he is weak in that aspect, it is surprising," Mouratoglou said. "I do not mean that the problem isn't there, but for some years there wasn't a player who thought he could beat him on clay. They all went on the court already defeated. Now things are sure to change."