I'm sure Arsenal will win in this match, Chelsea is a bad team and can't compete against top teams.
Chelsea previous matches: they beat Brighton which currently in bad performance too, Fulham and Burnley (two mediocre teams).
Arsenal previous matches: they beat Manchester City aka toughest team, unlucky lose against Lens (but Chelsea is worse than Lens).
So it's obvious Arsenal will win, the odds is high too, don't miss to bet Arsenal to win @2.15.
Even if the confidence in Arsenal is high but I don't think we can consider Chelsea bad and underestimate them now.
In terms of performance Chelsea are still at the bottom and that's true so Arsenal are worthy favorites in this match it's just that we can't completely doubt Chelsea and think they can't play because even though the beginning of this season they were not too erratic even seemed bad but in some matches they were able to bring 3 points in the last few matches on the other hand, Liverpool have also been held to a draw by Chelsea so I think even though currently Arsenal are above them but Chelsea can't be underestimated.