Nikolay Davydenko admits players in the ATP locker room "laugh" at Andy Murray's body language on court.
The British number one has come in for criticism recently for his demonstrative way of dealing with on-court aches and pains, with former Wimbledon champion Virginia Wade describing him as a "drama queen".
Davydenko, 31, also believes looks can be deceptive when it comes to the fitness of his Wimbledon first-round opponent.
"We just laugh sometimes," he said in The Sun. "Sometimes he walks on court, he looks tired, like he doesn't want to run anymore, and then he runs like an animal. He has done that all his career."
He continued: "He may have a pain somewhere but if you ask any player they will all say they have pains here and there.
"Nobody says they are perfect. It's just not possible."
Davydenko also suggested 25-year-old Murray may struggle to secure a grand slam title having failed to do so in his career so far.
"Murray has reached the Australian Open final but it doesn't look like he has enough to win it," he said.
"When you look at Rafa Nadal, Roger Federer and Novak Djokovic they look like different players. I think it's difficult for him to go to that level."
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