The FA are looking into comments made by Chelsea manager Andre Villas-Boas about referee Chris Foy following the Blues' 1-0 defeat to QPR.
The Chelsea boss was extremely unhappy with the refereeing of the match at Loftus Road after his side finished with nine men following the dismissals of Jose Bosingwa and Didier Drogba.
In particular, he was said to be unhappy with Bosingwa's red card, who was deemed to be the last man as he pulled down Shaun Wright-Phillips, with John Terry claiming he was back to cover the right-back.
34-year-old Villas-Boas admitted he was "very aggressive" with Foy following the match and claimed the official did not treat the sides equally, saying: "he [Foy] lost it...he was card happy towards the [Chelsea] team."
The FA are aware of the comments and will decide whether or not to charge him with improper conduct by Wednesday afternoon.
If he were to be charged and found guilty, he could be fined or face a touchline ban.
It is not the first time Villas-Boas has complained about the performance of referees this season, with other instances coming against Stoke City and Manchester United.