Rafael Nadal has levelled criticism at long-time rival Roger Federer by claiming the Swiss is leaving his rivals to question the tennis authorities about the strains of life on tour.
Nadal and Andy Murray have been two of the most vociferous critics of the tour schedule amid fears it has become too demanding of the leading players.
There was talk among players of a possible strike following last year's US Open, where a host of them abandoned matches due to fitness and injury concerns.
There have been issues on which Federer has spoken out, and during the US Open he stated there were "a whole lot of issues to be sorted out with the Grand Slams and the ITF (International Tennis Federation)".
But Nadal contends that Federer is not using his influence as forcefully as he might, given his status as the most successful player in the history of men's tennis.
Speaking today in Melbourne ahead of the Australian Open, Nadal told a press conference with Spanish journalists: "I disagree with him.
"His (position) is easy: do not say anything, all positive, I am a 'gentleman', others get burned.
"We each have our opinion and maybe he likes the circuit. Me too, I like it, and I think it's better than most sports. That does not mean you cannot be better and that you should change things that are bad.
"I say a lot of good things about tennis, because thanks to this sport I have had experiences in my life I could never have dreamed of, but to finish your career with pain in all areas of your body is not positive.
"He finishes his career as fresh as a daisy because he is physically privileged, but neither Murray nor (Novak) Djokovic and I are fresh as a daisy."