Sead Kolasinac admits Arsenal teammate Mesut Ozil is "unhappy".
Ozil has made just three appearances in all competitions this season and is yet to complete a full ninety minutes for the Gunners.
His last featured in the 5-4 penalty shoot-out defeat by Liverpool, where he made two assists and was instrumental in a third before making way for Matteo Guendouzi.
"Mesut is a really driven player," Kolasinac told Premier League Productions.
"He is a bit unhappy at the minute but you would never see that in his training. He is doing everything he can. He is doing extra sessions to make sure he is at the level he needs to be."
He added: "Mesut is Mesut. He has got a lot of special qualities.
"For example, the opposing team might put two players on him rather than one - which creates a lot of space for others. That makes a real difference on the pitch and in the game.
"Everyone knows the quality he has, we have seen it. He is one of the top players in Europe and I think he can achieve a lot and really help the team further when he's back."