Maurizio Sarri was left fuming with Andres Christensen after the defender left the Chelsea substitutes bench 15 minutes early during the Blues' defeat to Arsenal at the weekend.
Christensen has struggled to build upon his promising 2017/18 campaign where he made over 40 appearances under former manager Antonio Conte, restricted to just 12 appearances in all competitions so far this season - including a solitary Premier League start against Wolves back in December.
According to The Times, Christensen abdicated his position on the Chelsea bench with 15 minutes left on the clock against Arsenal and returned to the dressing room after the Blues made their final substitution of the evening.
The Danish defender is understood to have told his teammates that he was temporarily leaving the bench to go to the toilet, but he did not return to the away dugout.
It is not yet clear as to whether Christensen was given permission to leave his place on the bench, but his decision has been noted by Sarri, who is said to be frustrated with the 22-year-old's actions.
There have been plenty of rumours suggesting that Christensen could be on his way out of Stamford Bridge, with the likes of AC Milan and Barcelona both previously expressing an interest, but Chelsea are unlikely to let him leave without demanding a huge fee.
This news coincides with Sarri's post-match comments from the game where he launched a remarkable tirade against his players.
"I have to say, I'm extremely angry. Very angry indeed," he said, as per BBC Sport.
"This defeat was due to our mentality, more than anything else. This is something I can't accept. This group of players are extremely difficult to motivate."