Chelsea accused referee Mark Clattenburg of using "inappropriate language" at two players during Sunday's Premier League match against Manchester United, and lodged an official complaint with the Football Association.
Clattenburg sent off two Chelsea players in the 3-2 loss to United at Stamford Bridge and allowed a contentious late winning goal to striker Javier Hernandez, who appeared to be offside when he scored.
"We have lodged a complaint to the Premier League match delegate with regards to inappropriate language used by the referee and directed at two of our players in two separate incidents in today's match," Chelsea spokesman Steve Atkins said. "The match delegate will pass the complaint to the Football Association."
The Premier League, which oversees the Professional Game Match Officials Board, had no immediate comment and has to give approval before topflight referees can speak to the media.
Premier League referees wear microphones in matches and their audio is usually heard by the other match officials during games.
Clattenburg is one of the FIFA candidates to referee at the 2014 World Cup in Brazil.