The Football Association will wait to receive referee Michael Oliver's report from Sunday's Manchester derby at Old Trafford before deciding whether to take action against United and City over an alleged tunnel bust-up after the game.
Sources have confirmed to ESPN FC that players and staff from both teams were involved in confrontations in the dressing-room area after City moved 11 points clear at the top of the Premier League with a 2-1 win against their neighbours.
Although match referees do not file reports on each game they take charge of, officials are expected to compile an extraordinary incident report should such circumstances warrant it.
The FA is expected to be in contact with Oliver and his assistants on Monday, from which point a decision will be made over possible charges.
Should Oliver mention the alleged bust-up, the FA could request CCTV footage in and around the dressing-room area from after the game.
United may also be forced to explain the incident late in the second-half when a flare was thrown onto the pitch, close to City midfielder Bernardo Silva.
Ederson celebrates Manchester City's victory over Manchester United. Photo by Victoria Haydn/Man City via Getty Images
Sources have told ESPN FC that United manager Jose Mourinho was involved in the fracas, which happened in the corridor connecting the home and away dressing rooms, as he walked past City's dressing room to the main tunnel area to fulfil his broadcast media interviews.
BBC Sport and PA Sport reported that Mourinho had milk and water thrown at him and shouted into the away dressing room, while it has also been claimed he was involved in a confrontation with City goalkeeper Ederson.
PA Sport also claimed that City coach Mikel Arteta suffered a cut to the head, with the Guardian adding he "was left with blood pouring down his face."
City did not respond to requests for comment.
ESPN FC's Manchester United correspondent, Rob Dawson, contributed to this report.
Source: espn.co.uk