Arsenal just need to defend so that Real Madrid don't score more than 2 goals, but this goal deficit is far enough that it's hard for Real Madrid to catch up, but don't let Arsenal have the same bad performance against Brentford... it could give Madrid a chance.
Still don't understand Arsenal, why in PL they can't win twice while in CL they can beat big teams with a landslide score, but this is football sometimes full of surprises.
Play more defense is not good tactician and get difficulty under pressure from Real Madrid more than 90 minutes, I don't think Arsenal have strong defend how the opponent teams get controlling the games and Real Madrid have good tactician with offensive games play.
Arsenal have advantage by winning three goals at the first leg but full defense game at second leg I think make Arsenal difficult for defending their three winning goals capital for second leg match how often Madrid make comeback at Champion League matches.
For second leg matches most crucial than first leg, Madrid get advantage as home match and have reputation as teams always success comeback after defeating at first leg match although in this moment Madrid not scoring one goal yet at first leg match.