Serge Aurier reportedly left the Tottenham Hotspur Stadium at half time of the defeat to Liverpool on Thursday night.
Spurs succumbed to a 3-1 defeat against their Premier League title rivals, the first goal coming seconds before half time after a cross from Spurs' right-hand side.
With Mourinho going with a back three, Aurier was being used as a wing-back, and his positioning played a part in Sadio Mane being able to provide Roberto Firmino with a close-range finish.
According to the Daily Mail, Mourinho was critical of his players at half time, something which is said to have led to 'angry exchanges' between members of the group.
Aurier was nowhere to be seen during the second half, allegedly because he had opted to leave the ground after being informed of his substitution.
Mourinho acknowledged after the game that players had 'been unhappy' at the midway point of the fixture in North London.