Manchester United manager Jose Mourinho has been contacted by the Football Association after saying it would be "difficult" for Anthony Taylor to referee Monday's game at Liverpool.
Mourinho said appointing Taylor for the game had put "pressure" on the Manchester-based official.
Managers are not supposed to speak about referees prior to matches.
The Portuguese, 53, has until Friday to offer a response, which will then be considered by the FA.
Monday's game finished 0-0.