An exasperated Andy Roddick said the ATP men's tour must give players more time to rest during the season or risk shortening their careers.
The world number six lost to qualifier Lukasz Kubot in the first match of his title defence at the China Open last week and said then that the top players were playing too much tennis.
He renewed his attack at the Shanghai Masters on Monday while admitting the ultimate negotiating tool, a players' strike, was unlikely.
"I think it's ridiculous to think that you have a professional sport that doesn't have a legitimate off season to rest, get healthy, and then train," the 27-year-old told reporters at his 16th tournament of the season.
World number one Roger Federer pulled out of Shanghai citing fatigue, while number three Andy Murray blamed a wrist injury for his absence from the inaugural $3.24 million tournament.
"I don't think that's all of one big coincidence, and I just hope that the shortsightedness doesn't affect the length of careers," he said.
"I think in tennis you definitely want your stars around as long as possible," he added.
The top 30 men's players are obliged to play the four two-week grand slam events and eight of the nine Masters Series tournaments.
In addition, their best four results in ATP 500 events and best two in lower level tournaments count towards their rankings, effectively meaning they must play at least 18 a year.
"We've been talking about this forever, and now we get slapped with mandatory tournaments," said the 2003 US Open champion.
"We don't really have a whole lot of choices in the matter, which I don't think is the right way to go about it."
CONFLICT OF INTEREST
Roddick thought the men could learn from the WTA women's tour, which reorganised its calendar for this season and reduced the number of mandatory events from 13 to 10.
The American expressed his frustration that the people with the power to change things were often the same people who ran the tournaments, which was "a little bit of a conflict of interest".
The players were unlikely to boycott an event, however, he said.
"I don't think any of us wants to (strike), because even more so than feeling a responsibility to the powers that be in tennis, we feel a responsibility to the fans," he said.
"We don't want to alienate our fans. It's a tough situation, and that's why I think that we've put up with it as long as we have."
Spain's Rafa Nadal agreed with the American that the playing year was too long.
"It's impossible to play from January 1 to December 5, no sport can do it," said the world number two. "I don't know what the solution is, but it must be changed and soon."
