Players union chief Gordon Taylor has expressed his disappointment and concern at Carlos Tevez's latest indiscretion after the striker today failed to report to training with Manchester City.
Tevez - despite apparently being told by City that he was not permitted to - flew out to his native Argentina on Monday night to see his family.
Tuesday was a scheduled day off for the 27-year-old, but he was due at City's Carrington training ground this morning and did not show up.
The news comes just a day after it emerged that Tevez would not be appealing against the club's ruling that he was guilty of misconduct in the Champions League defeat to Bayern Munich on September 27.
City last month fined Tevez four weeks' wages and suspended him for two weeks - deemed to have already been served - after a disciplinary panel found the former Manchester United man guilty of five breaches of contract relating to his behaviour on the bench during the 2-0 loss at the Allianz Arena.
The Professional Footballers' Association become involved, making an intervention that saw the fine cut to two weeks' wages, and having backed Tevez on that occasion, PFA chief executive Taylor has been left dismayed by the fresh turn of events.
"To say the least, I am very disappointed and extremely concerned now," Taylor told Sky Sports News.
"To go out to Argentina when - as I have been informed - he was clearly told not to because they (City) needed to work on his fitness, and to blatantly ignore that instruction starts to affect any chance of any reconciliation now.
"The whole relationship between clubs and players is one where there has to be clear understanding of what is to be expected and what is not expected.
"From that point of view, he is making it virtually impossible to have a reconciliation and leaving himself very vulnerable to strong action by the club.
"If he is determined to leave the club, which may well be apparent, then his money value is being diminished by his actions and can affect another club's interest.
"As such, he could be held responsible for that, so it is getting to be a situation that I am not at all happy about.
"Neither are the club of course, and it is one that we will have to deal with."
A spokesman for City told Press Association Sport they were not yet able to say what punishment may follow for Tevez, the controversy around whom shows little sign of abating.
The player was accused by manager Roberto Mancini of refusing to come on as a substitute during the second half of match in Munich, but Tevez denied the allegation and blamed a misunderstanding, insisting he had merely refused to warm up - something he felt unnecessary as he had already done so.
He was suspended for two weeks then began training alone while the matter was investigated, and on October 25 City announced they were upholding a charge of misconduct against him based on the panel's findings.
The PFA fought Tevez's corner to get the sanctions reduced, but Taylor is uncertain what now lies in store for the former City captain.
"I have been accused at times of defending the indefensible," Taylor said.
"It is very difficult to now be in a situation where we put our heads on the block.
"I do feel very disappointed to say the least that when I was hoping things could move on, it has gone into reverse and now he is left in a position that becomes very vulnerable.
"The lad is digging himself a hole and it is going deeper. It is a worry to me how we can now get out of this.
"He is a human being and a top-quality footballer, but his actions are not what we could possibly recommend to any other player in the game.
"It goes to the heart of the contract and that could be gross misconduct in anybody's language.
"I don't want to predetermine, but I am very concerned because it is a serious situation and one that the PFA are not happy about."
Tevez's future with City remains unclear, although Mancini did recently suggest the frontman - who was the club's top scorer and skipper last term as they won the FA Cup, but has fallen out of favour since his failed attempt to secure a transfer over the summer - could yet return to the team if he apologises.
Tevez has only made five appearances for City this season, with the last coming on September 21, and he has not been selected by Argentina for their World Cup qualifying double header against Bolivia and Colombia during the current international break.