Gunners boss Arsene Wenger said: "If Jens' situation has not changed in January we will have to see what decision he takes.
"But, at the moment, we are in the middle of November and there is still plenty of time to win his place back.
"You will never find a manager who says it's easy to leave a player out.
"But you have to make a decision and no matter who you choose you will make someone else unhappy.
"You feel sorry when someone does not play but that is a part of my job."