Yeah both teams are in different situations this season we can't compare their performance based on last season's matches and each team has its own advantages, here in the first leg Arsenal are very favorites to win then in the second leg of course Bayern Munich are the favourites well as I said before the goal difference will determine who will go to the next stage. One thing I note is that Arsenal is on fire in the Premier League while Bayern Munchen are not doing much better due to some recent bad results..
This was a fierce battle especially as Arsenal wanted revenge against Bayern Munich after Arsenal's massacre in the past, with Bayern scoring five goals in a match against Arsenal at least three times. Moreover, Arsenal is on fire this season, even in first place in the EPL league, and Arsenal's game is much better under Arteta.
However, it is true that this season Bayern Munich's performance is much worse than Arsenal, but they still have more experience and especially since they almost lost the Bundesliga title race to Leverkusen, you can be sure they will put all their concentration on the UCL. So they also have full potential to win in the UCL, at least they can win one of the two matches. Because of course Arsenal's concentration is still divided between the EPL league and the UCL league.
I am sure Arsenal players are not thinking about past as their current performance and quality is amazing and with this level of game they can change the history which is now into their hands with they needed confidence and better depth for beating team like Bayern Munich which is also not at the level which was they had in past due to transition period even they are going to give their best in this match as this is only chance for them to have any trophy after losing their all chances in Bundesliga.
Mikel Arteta is doing good job and his strategy is having good results for him which are clearly indicating they are on verge of changing history and going to have their best in this event after decades of bad results, Arsenal is now clearly looking for the success in all events.