Arsenal manager Mikel Arteta has dropped Pierre-Emerick Aubameyang for Saturday's Premier League game against Southampton due to a "disciplinary breach."
The 31-year-old was not present at training on Friday and although the club have refused to specify the exact nature of the incident, a club source told ESPN it is "not COVID related."
Speaking before kick-off, Arteta said: "[Aubameyang is missing] unfortunately due to a disciplinary breach.
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"I think we have been very consistent that we have certain non-negotiables in the team that we have set ourselves as a club, and he's not involved today."
Asked if it was a long-term punishment, Arteta added: "It starts today. Certainly it's not an easy situation, or a situation that we want to have our club captain in."
Aubameyang was left out of the matchday squad for March's north London derby win over Tottenham after arriving late for a team meeting on the day of the game.
This latest issue will raise further questions over Arteta's relationship with Aubameyang after the club captain was restricted to a five-minute cameo as a substitute in Monday's 2-1 defeat at Everton.
Asked about Sky Sports' pundit Gary Neville's claim that things were threatening to "turn a little sour" between Arteta and Aubameyang, the Gunners boss said on Friday: "I have a very good relationship with my players. Everyone has to understand that I always do the best for this club and for this team. And often if that can benefit any individuals, I will always do it. The decisions are not personal, the decisions are just to get performance, and the best out of the team. That's it.
"Obviously, when a player is not scoring it's affecting his confidence, it's affecting the mood and probably the belief, but you have to rebel against this situation, don't accept it and feel sorry for yourself."
Pushed on whether Arsenal were considering allowing Aubameyang to leave, Arteta added: "Really, we have never discussed something like this, and when players are under difficulty -- or the team is under difficulty -- what we have to be is supportive."