Chelsea boss Andre Villas-Boas insists he has nothing to apologise for after blasting ref Chris Foy in the aftermath of their bitter defeat to QPR.
Villas-Boas has been asked by the FA for an explanation of his criticism.
The 34-year-old stood by his words, something that could land him in even more trouble.
"I don't think I said anything I shouldn't have," Villas-Boas said. "I would never question the referee's integrity.
"But the fact is that, at the moment, we are paying heavily in terms of major decisions. Maybe this is what the FA (don't) want to hear from me - phrases like, 'The referee has influenced heavily three of our games'."
Villas-Boas accepted officials were only "human" but reiterated his attack on what he claimed was inconsistency in Foy's "extremely unfair" decision-making.
"If you go one route, you have to stick to it for the rest of the game," he said.
"With 11 players, we should have played better and there are mistakes we have to avoid and which are fair - you have to be criticised and evaluate yourselves and learn from those mistakes - but it's a very disappointing day for the referee, for Chris Foy. I will stick to my words."
He added: "Chris, for this particular game, was card happy and didn't show a pattern to what he's done in the past. What happened in that game was surprising given what he'd done before."