The FA have charged Chelsea in the aftermath of a bitter West London derby at QPR.
The FA wrote to Chelsea manager Andre Villas-Boas on Tuesday afternoon asking for an explanation for his criticism of referee Chris Foy and the official's two assistants.
Chelsea were also charged with "failure to ensure their players conducted themselves in an orderly fashion" after some of them appeared to surround Foy when Jose Bosingwa was red carded.
The Blues were given until Friday to respond on both counts, after which Villas-Boas could be hit with a charge for accusing the referee of not treating both sides equally and of being "card happy".