There are some motivations owned by arsenal to win this game. To make the gap to the city becomes even bigger, keep unbeating record, add chances to win the EPL title this season.
It's all have been motivating arsenal to win the game and that's it. I don't see other reason.
Of course their goal is EPL champions, then they must win in every EPL match. So they must not lose points in big games. Although Chelsea may not currently look strong, but they can make a surprise for Arsenal.
Maybe Arsenal should be able to seize Man City's current moment. Man City are not in good shape and dropped some points. They must also work smartly to learn from Arsenal's mistakes late last season. They must keep it stable.