Sir Alex Ferguson has accused Jose Mourinho of lacking respect for anyone but himself.
The Manchester United boss is fuming with his Chelsea counterpart over an apparent attempt to put referees under pressure to give penalties against the Red Devils during the latter stages of the title run-in.
Ferguson is particularly angry about Mourinho's suggestion the rules are being manipulated to aid United's championship quest, with the Blues coach citing a number of recent decisions that have gone against his team.
And the Scot noted with disdain that Mourinho got round a UEFA touchline ban by hiding in a laundry basket in order to administer his team talks as normal.
"The story about him jumping into the laundry basket to do his team talk just shows he snubbed his nose up at UEFA," Ferguson told MUTV.
"It tells you that he doesn't respect anyone but himself. That is dangerous."
Given Mourinho's weekend comments about different rules now being in operation, followed up by his claim fellow countryman Cristiano Ronaldo is 'a liar' for questioning the motives behind the original attack, Ferguson cannot understand why the Football Association have not stepped into the row.
While he accepts penalty claims for both Sheffield United and Middlesbrough recently could easily have gone against his team, Ferguson believes Mourinho's reaction has gone much too far.
"It seems to me a couple of decisions have gone for us," said Ferguson.
"I know John O'Shea got the ball against Middlesbrough but a lot of referees would have given it.
"But the suggestion we have changed the regulations is bringing a suspicion into the game that we are corrupting it. That is a hell of a statement and it is wrong.
"Once you bring that kind of suspicion into our game, which is the most honest in the world, then we are finished. Our principles will have gone
"It is a calculated attempt to put pressure on referees to give penalty kicks against us.
"The FA should have done something about that. They have refused to do it."