Real Madrid is not a small team Arsenal will not be afraid of because, they have heard what Real Madrid is doing in the la Liga league and other tournament which they can still do those things to flog Arsenal with many goals to cause fear to other teams in that group. Real Madrid must break the record in this game to beat Arsenal to make people believe that things has changed in this season because their management has signed in so much talented players that will make the game favour Real Madrid. If wolves can beat Manchester city in the premier league to surprised people, I believe something like that will surely happen in this game that will make Real Madrid to achieve what they have never achieve before in the champion league.
Real Madrid team is not in a state to flog Arsenal now as you are thinking because they only have vast Champions League experience more than Arsenal because they are the team with highest Champions League trophy in the world and Arsenal did not have even one, but that should not be used to judge Arsenal case now because Arsenal team is more reliable than Real Madrid team that was struggling to win matches in Laliga just because some players were injured.
Even with their injury crisis, I predict Real Madrid will win their group in the current Champions League standings. That says a lot about their tenacity and history in Europe. However, I wouldnt discount Arsenal merely because of Real's success in Europe. According to what I've seen, Arsenal has a talented group, and Arteta is undoubtedly working hard to improve their performance; especially in light of the points they dropped against Lens. Although Real Madrid may have Champions League experience, it is impossible to discount Arsenal's current performance and dependability. It would be exciting to see how they would interact if they faced off.