Mikel Arteta was challenged by an Arsenal player in front of the rest of the squad.
Mirror Sport understands that the player, who hasn't been named, voiced his frustration that some individuals are being treated differently at Arsenal.
The incident took place during a team meeting.
Arteta is struggling to keep his head above water at Arsenal at the moment, with problems on and off the Emirates pitch.
The Gunners have won back to back matches in the Premier League against Chelsea and Brighton, which has relieved some of the stress.
But Arsenal have still had an extremely disappointing 2020 and are floundering down in 13th - nine points adrift of the top four places.
Sead Kolasinac left Arsenal on a half-season loan this Thursday, with the defender joining Bundesliga club Schalke.
The left-back is the first player out the door at Arsenal, in what could be a busy month with Arteta looking to remove the deadwood.
Arteta, who took the reins from Unai Emery in 2019, was very much on the chopping block ahead of Arsenal's wins over Chelsea and Brighton.
Following the 1-0 victory over the Seagulls, a rejuvenated Arteta told the press: "Any manager it's hard enough considering the context - it's been quite a challenge.
"I've suffered in some moments but I have great people around me.
"This period has been so important. We had a tough week, it wasn't so much about performances but about results yet you need results to start the confidence.
"Now with two wins, everybody is in a better mood. We've managed to get through this period while maintaining our team spirit and cohesion.
"It has been frustrating with defeats and that can affect the team but hopefully we can now go on a runs in a positive direction."
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