The Football Association has asked Manchester United manager Jose Mourinho to explain comments he made about referee Anthony Taylor before his side's goalless draw against Liverpool at Anfield on Monday, it said on Tuesday.
Mourinho said it would be "difficult" for Taylor, who is from the Greater Manchester area, to have "a very good performance" after being put in charge of the game between two fierce rivals.
FA rules prohibit managers and players from making comments about officials which could be viewed as intimidatory or influential before games.
Mourinho has until Friday to respond.
(Reporting by Simon Jennings in Bengaluru,; Editing by Neville Dalton)