PFA chief executive Gordon Taylor admits Carlos Tevez is 'digging himself a hole' at Manchester City and risks incurring further disciplinary action.
The Argentine striker missed training on Wednesday and has returned to his homeland, despite being repeatedly told that he was to remain in this country.
His decision to go against City's orders comes on the back of his infamous non-appearance in a UEFA Champions League clash against Bayern Munich that saw him dominate the headlines.
The PFA fought his corner on that occasion, resulting in a four-week fine imposed by City being cut in half.
Taylor, though, admits that Tevez has now left himself 'vulnerable' with his latest actions and believes City could decide to wash their hands of the troublesome South American by seeking to cancel his contract.
"To break an instruction not to go and to be determined to go is inviting trouble," he told Sky Sports News HD.
"From that point of view, I believe there is going to be more trouble rather than peace in this situation.
"I do feel very disappointed to say the least, coming so soon when I was hoping things could move on. It's gone into reverse and now he is left in a position that becomes very vulnerable. I'm sure it's not only me, his advisors as well must be wondering where do we go from here?"
Asked if City were now in a position to consider ending Tevez's contract, Taylor said: "Bearing in mind what's happened recently, he was clearly told - I have been informed - on more than one occasion that he was not to return to Argentina, that he was on a fitness regime here. He has not been in the team and if he has breached that instruction, that goes to the heart of the contract and that could be gross misconduct in anybody's language.
"From that point of view, I don't want to predetermine, but I'm very concerned because it's a serious situation and one that the PFA aren't happy about and I assume neither are Manchester City."
Taylor has stopped short of pulling the PFA's support of Tevez, but admits it would be very difficult for them to stand up for the forward in the wake of his decision to go AWOL.
"I don't put off players, even when they are in the wrong," he said.
"But, on the other hand, we would have to advise him that at the moment his actions are not doing himself any good at all and he is leaving himself very vulnerable to action by the club, and that could be that they will consider very serious actions so soon after the last problem.
"From that point of view, it's no use saying otherwise, the lad is digging himself a hole and it is going deeper.
"It's a worry to me how we can get out of this, bearing in mind that he is a human being and a top quality footballer. His actions aren't what we could possibly recommend to any other player in the game."