Shanghai:World number six Andy Roddick lashed out at plans to force players to turn up to more tournaments after joining Rafael Nadal on the Masters Cup injury list.
Roddick refused to blame the rigorous tennis schedule for his "unlucky" ankle injury but said too much pressure was being put on players, including Nadal.
"I think too much is asked of us as far as playing 11 months of the year, and now they're imposing more mandatory tournaments," Roddick said.
"It doesn't make a whole a lot of sense. It's unfortunate for someone like Rafa that goes out there and does things the right way. No one is ever going to question how much effort he gives every time he's on the court.
"I don't think anybody wants to be on the court more than he does, so at a certain point you would hope they start respecting our opinions a little bit more."
Tennis officials have announced a revamped schedule for 2009 with top players expected to attend eight out of nine 'Masters 1000' events plus four lower-tier tournaments.
With the Australian Open in January and the season's climax, the World Tour Final, in November, successful players may only have one month's rest per year.
Roddick pulled out shortly before his group match in Shanghai with defending champion Roger Federer yesterday.
Nadal withdrew with knee tendinitis and is also skipping Spain's Davis Cup final against Argentina.
"This particular injury had nothing to do with it being a long season. It was an accident and it was unlucky it happened," Roddick said.
"That being said, I think I've been pretty forthright in my opinions on regarding the schedule and it being too long."
Injury worries have threatened to overshadow the tournament with Federer carrying a back problem and Argentina's Juan Martin del Potro nursing a split big toenail.
The equivalent women's event lost top draws Serena Williams and Ana Ivanovic due to a stomach injury and virus respectively.
Concerns over the crowded schedule have long plagued tennis. In 2005 Chinese organisers voiced anger when Roddick, Nadal, Andre Agassi, Lleyton Hewitt and Marat Safin all missed the Masters Cup.