Matteo Guendouzi clashed with a teammate during Arsenal's Dubai camp, it has been claimed.
The Athletic reports Guendouzi's omission for the Newcastle clash was due to a fracas with a teammate during the Gunners' winter break in Dubai - where he was deemed the aggressor.
Arteta was forced to pull the pair apart with Guendouzi being sanctioned for his part in the melee.
But the 20-year-old was also reportedly given a telling-off by Arsenal technical director Edu for a separate incident off the training pitch.
Guendouzi allegedly removed his shirt at an external event and waved it around in support of a local music act.
However since then, Guendouzi is said to have impressed Arsenal with his response and there is still a belief within the club that he can develop into a top player.