Andre Villas-Boas has revealed he has complained to referees' chief Mike Riley about the performance of the officials in Chelsea's defeat at Manchester United.
Villas-Boas was unhappy with a number of decisions that went against his side as they slumped to a 3-1 defeat at Old Trafford.
Chelsea fell 2-0 behind at Old Trafford on Sunday to goals which replays showed should not have stood as both scorers had been offside.
Villas-Boas believes his side were let down by the officials at Old Trafford feeling their decisions had a massive impact on the result of the game.
"Very, very unhappy with a poor performance from the referees, which in the end had a decisive role in the result, and I don't take it very, very lightly," insisted Villas-Boas.
"You expect the linesman to do his job.
"I already went further ahead with the situation by speaking to the correct people.
"We all feel very, very down when the referee had such an impact on the result."
Villas-Boas is the second top manager to speak to Riley after Liverpool boss Kenny Dalglish spoke to the general manager of the Professional Game Match Officials following his side's defeat to Stoke earlier this month.