Playing more defensively and strengthening the defense line as well as building and gathering players in the defense area is a must for Arsenal, because their opponent is Real Madrid who is known to be able to make a comeback even though they are in a disadvantageous position in the first leg because they suffered a big defeat and that always happens and this is what Mikel Arteta must think about and plan very carefully.
In two latest seasons include this current season, Arteta has tried to train and order his players to play very defensive carefully and they have quite good defense system. Their defensive system is not yet like a bunker as in Premier League after 32 matches they got 27 conceded goals, but in their good matches in defense, their opponents surely struggle to find space, hole and access nearly to Arsenal box and goalkeeper.
However, I am sure Mikel Arteta already knows and plans everything and will also motivate the players to play very carefully and also focus on paying attention to Real Madrid's attackers to continue to put pressure because pressure is something that can make it difficult for attackers to penetrate the defense to be able to score goals. And if you look at their current performance, I am optimistic that Arsenal can maintain their advantage even though Real Madrid won this match but the aggregate victory remains on Arsenal's side, because 3 goals without reply in the first leg is a very good provision.
With great advantage with three goal difference from a first leg, and with their good defensive system, Arsenal will be able to play defensively well to secure three goal advantage that is amazing difference for them before the second leg. Arteta and his players know very well that they don't need a win in Bernabeu, they need to come there and secure their three goal advantage, as well as avoiding unwanted cards and player suspensions for semi finals.