Jose Mourinho will sue Uefa referees' committee chairman Volker Roth over accusations that the Chelsea boss is the "enemy of football".
The bizarre blast from UEFA against Mourinho is the result of the retirement of ref Anders Frisk.
The Swedish referee announced last week he was stepping down as a result of death threats.
Frisk referred Chelsea's 1st leg knockout stage Champions league match against Barcelona.
The Blues lost in Spain 2-1 and had Didier Drogba sent off.
Mourinho then claimed that Frisk and the Barca manager Frank Rijkaard had a 'chat' at half-time.
The fallout from this is that now Voth is in the dock and Chelsea will, pursue legal avenues to preserve the integrity of their manager.
Roth said: "We can't accept that one of our best referees has been forced to quit because of this. People like Mourinho are the enemy of football."
Mourinho countered: "Mr Roth has two ways out, apologise or it goes to court.
"It's a shame that Frisk has decided to leave football.
"If, as some people have suggested, this decision is linked to the criticism of his performance in the Barcelona game, it seems strange to me.
"There's similar criticism every day, all around the world, for managers, directors and players. It's a normal situation.
A referee with the experience of Mr Frisk would not take such a drastic decision because of criticism of his performance at Barcelona.
If it has something to do with the threats - which should obviously be condemned - then it is a police case."