Arsenal will only try their best to see how they can outsmart Madrid but it wouldn't be easy, because Madrid attacking pressure will sweep them off their feet. Real Madrid is not going to allow any laxity from their side that will make them not qualify to the semifinals. I feel this is end of road for Arsenal in this competition.
The chances are indeed small because the strength possessed by Arsenal is not balanced enough to face Real Madrid and mentally and experience are also quite different for both teams. The only chance of a draw but if that is the result it will not benefit Arsenal because the second leg will be played at Real Madrid's home. Arteta will try to improve the pattern of play to press because victory in the first leg is quite important.
Facing Real Madrid who are mentally much better might be a little more difficult, even though the first leg will take place at Arsenal's home and I also predict this is the last step for Arsenal to survive in the Champions League because they are not strong enough to face Real Madrid.