Ruben Amorim will speak privately to Alejandro Garnacho after the Manchester United winger headed straight down the tunnel after being substituted in the first half.
Garnacho was bright in a rollercoaster first half but was the player sacrificed after Patrick Dorgu was shown a straight red card and Manchester United were reduced to 10 men.
He was replaced by Noussair Mazraoui on the stroke of half-time, a decision which large sections of the home crowd audibly booed, before trudging straight down the tunnel back to the dressing room.
After the match and moments before Amorim faced the media in his press conference, Garnacho posted on his Instagram story a picture of him walking down the touchline towards the tunnel without a caption.