Caroline Wozniacki has alleged that the WTA "forced" her to play in her Rogers Cup second-round loss to Belinda Bencic, even though she is struggling with a calf injury.
World number five Wozniacki wore heavy strapping on her left calf throughout her 7-5 7-5 defeat to Bencic in Toronto on Wednesday.
The Dane indicated afterwards that she had not been able to practice due to the injury, but could not pull out due to WTA rules.
"The rules are if you're a top-10 player, that this was my commitment tournament, you're forced to play," former world number one Wozniacki said.
"If you don't, you get huge money fines. You get zero points to your ranking... which is crazy."
Wozniacki continued: "The WTA is all about: 'We want the players healthy, we want them to play at their best level at every tournament and we want to make it tough for them.'
"That's good, but the fact that they're pushing you to play whenever, if you are not feeling 100 per cent, is not okay."
Wozniacki was also knocked out in the second round in Stanford last week, and will hope her calf problem clears up before the US Open, which begins on August 31.