Real Madrid beat Villarreal 1-0 at the Santiago Bernabéu on Saturday, but the victory was overshadowed by the Brazilian forward's sending-off and the possibility of a suspension extending beyond one match.
Referee Isidro Díaz de Mera explained that Vinícius was dismissed in the 73rd minute for pulling an opponent's hair while the ball was in play and not being contested between the two players.
The incident occurred during the move that appeared to produce a second Madrid goal. Vinícius found the net, but the goal was disallowed after a VAR review identified the infringement, and the forward was shown a straight red card.
The referee's report also described the player's conduct after the decision.
“With play stopped, the home club's number seven, Vinícius José de Oliveira do Nascimento, after having been sent off and still being on the field of play, continued protesting my decision, shouting loudly and heading towards the area where I was, with an aggressive attitude,” Díaz de Mera wrote.
The official added that Vinícius “had to be restrained by teammates”, while noting that he could not identify any specific words or expression used by the player.
The report could prove significant when the disciplinary authorities determine the length of the suspension. The Spanish refereeing committee's protocol categorises hair-pulling against an opponent away from a contest for the ball as violent conduct, potentially carrying a punishment longer than a single match.
Madrid face Sevilla in their next league fixture before travelling to Barcelona for El Clásico on 25 October. A ban of two or more matches would therefore rule Vinícius out of the meeting with their rivals.
The final sanction has not been confirmed, however, and the length of any suspension will depend on the disciplinary decision rather than the referee's report alone.
Vinícius was not the only figure dismissed or disciplined during a tense evening at the Bernabéu. Madrid's goalkeeper coach Nuno Santos was sent off, while Villarreal's delegate Xisco Nadal also received a red card. José Mourinho and Madrid delegate Chendo were shown yellow cards.
Madrid held on to their lead despite finishing the match with ten men, with Yan Diomande scoring the decisive goal. The result secured three points, but the disciplinary consequences of Vinícius's dismissal could have a significant impact on the club's upcoming fixtures.