Mark Clattenburg lodge complaint with English FA over referee 's `` inappropriate language '' John Obi Mikel reportedly used racial language towards Chelsea . FA launch investigation after reading match report from Clattenburg on October 2011 . All four match officials -- the referee , his two assistants and the fourth official -- wore microphones and ear pieces that allowed them to hear what each other was saying throughout the match . Clattenburg welcomes opportunity to establish facts in case with few precedents .
Mark Clattenburg lodge complaint with English FA over referee 's `` inappropriate language '' John Obi Mikel reportedly used racial language towards Chelsea . FA launch investigation after reading match report from Clattenburg on October 2011 . Clattenburg welcomes opportunity to establish facts in case with few precedents .