Sir Alex Ferguson has described the rule which forced Manchester City to halve the fine they handed to Carlos Tevez as "a bit crazy".
But the Manchester United manager insisted the rules agreed by the Premier League, FA and PFA state that clubs could only fine players two weeks' wages - and that there was nothing City could do about it.
City had to cut Tevez's fine to two weeks' wages after the Professional Footballers' Association (PFA) refused to support a four-week penalty for the striker refusing to play.
The club have since claimed the PFA have a "conflict of interest" in both representing Tevez and then being in a position to rule on the sanction he faces.
Ferguson said today: "I think it is a bit strange of course but the regulations are there. It is a fact that the maximum fine you can give a player is two weeks' [wages].
"It seems a bit crazy in that particular situation but it's there and there's nothing you can do about it."
The Argentina striker was found guilty of five breaches of contract by City, including a refusal to play.
The PFA stated they believe Tevez "never refused to play for the club" and that there was "no justification for a fine other than up to the prescribed sanction of two weeks' wages agreed by the FA, the Premier League and PFA".
Two weeks' wages in Tevez's case is thought to be around £400,000.
PFA chief executive Gordon Taylor this morning defended his and the PFA's position, following City's conflict of interest claim.
Taylor told BBC Radio Five Live: "It's not a conflict of interest at all.
"It's just merely pointing out what the law is, what the law says, and what the code of practice says."
Taylor explained: "It's like a QC having to tell the judge that in accordance with the law you've got it wrong."