Uefa has opened disciplinary proceedings against Manchester United and Nani following the club's defeat to Real Madrid on Tuesday evening.
The Portuguese winger was sent from the field during the Champions League last-16 second-leg after connecting with Los Blancos right-back Alvaro Arbeloa with a high boot.
That decision left manager Sir Alex Ferguson infuriated, and the 71-year-old sent assistant Mike Phelan in his place to fulfil the club's media obligations after the game.
Phelan revealed that Ferguson was "too distraught" with referee Cuneyt's Cakir's performance to face the press in the immediate aftermath, despite his absence contravening Uefa rules.
The Red Devils also face sanctions over their failure to provide two players for press interviews after the game.
The current Premier League leaders could face further disciplinary action should veteran defender Rio Ferdinand's sarcastic applause of Cakir shortly after the final whistle be mentioned in the official's report.