Comments made by Chelsea manager Andre Villas-Boas about referee Chris Foy's performance in the 1-0 defeat against QPR are being looked into by the Football Association.
Chelsea's manager launched a verbal attack on Foy on Sunday after seeing his side end the match at Loftus Road with nine men following the dismissals of Jose Bosingwa and Didier Drogba.
Villas-Boas was unhappy with the sending-off of Bosingwa, who was deemed to be the last man when pulling down Shaun Wright-Phillips despite John Terry claiming he had the Portuguese full-back covered.
The 34-year-old manager admitted he was "very aggressive" with Foy after accosting him following the West London derby defeat and said the official failed to treat both sides equally, adding: "he (Foy) lost it.. he was card happy towards the (Chelsea) team."
It is understood the FA is aware of the former Porto manager's comments and will decide whether or not to charge him with improper conduct by Wednesday afternoon.
Should he be charged and found guilty, Villas-Boas could be fined or even suspended.
Villas-Boas, who took over from Carlo Ancelotti as Chelsea manager this summer, has complained about the performance of officials in the club's games against Stoke and Manchester United, and said on Sunday he felt his team were not being treated fairly by referees.