Manchester City manager Pep Guardiola has been asked for "his observations" following his recent comments about referee Anthony Taylor, the English Football Association has confirmed.
The City boss said the offical would "try to do his best job" when asked the decision to appoint the Manchester-based official for Sunday's Manchester derby.
An FA spokesman said: "The FA has sought observations from Pep Guardiola regards his pre-Manchester derby media comments. He has until 1800GMT on Thursday to provide them."
The appointment of Taylor -- a supporter of non-league club Altrincham, which is based in Greater Manchester -- was criticised because he comes from the same city as the two teams.
Although Guardiola offered no criticism of the referee, managers are not supposed to discuss referees in pre-match news conferences, even in a complimentary manner, although it does not automatically result in a sanction.
Asked about Taylor taking charge in his news conference on Friday, the City boss said: "He is going to try to do the best job like we try as managers and football players.
"Mr Taylor is going to try and make a good time. The important thing is to focus on our game and of course knowing which opponent we are going to face and that is all.
"Hopefully they can make good decisions for both sides, and a good game, like all England and all Europe is going to watch us. That is the most important pleasure.
"The referee doesn't want to make a mistake. He knows everyone from around the world is going to watch him and he doesn't want to make a mistake, that is pretty sure. But, if he is fan of United or City, everyone can be a fan of whoever he wants so no problem."
Although Taylor awarded a penalty to United in the second half of City's 3-1 win, the game passed off without any controversy.