If Arsenal let Real Madrid score first, this match can end with so many goals from both sides and likely Arsenal will be destroyed in Bernabeu. If Arsenal can play carefully and tightly, this match can end without goal.
Be sure of one thing, there will be goals at the Bernabeu, and they will probably be from Madrid, it is a fact that they will come out with everything they have, they will come out with a formation in which they will suffocate Arsenal and drop by drop the glass will overflow, I am completely sure that Arsenal will play in defense mode and appeal to the counterattack , there will be no other option for Madrid, and holding out for 90 minutes like that is very difficult, Madrid will not give up on their attack, even if the players do not recover after the physical effort, but it will be like that.