Arsenal are more focused on the match against Real Madrid in the second leg of UCL, they managed to get through the last match without a single player being injured. Withdrawing from the EPL title race was a must as it was almost impossible to catch Liverpool points tally.
Regarding Real Madrid situation under pressure after losing 3-0 on aggregate in the first leg, they will try to make a comeback, but I'm not sure they can do it considering Real Madrid have never scored against Arsenal when the two teams have visited.
Both Arsenal and Real Madrid will focus on the second match that decide the winner and who will move to semi final phase of UEFA Champions League. Arsenal know that they are holding very great advantage but it does not mean they already are qualified for semi finals. They also know that Real Madrid made many impressive comebacks historically and they are able to do another comeback. Surely Arsenal don't want to be a newest victim of Real Madrid, and together with ambition of Real Madrid for a comeback, this second leg quarter final between them will be very exciting.
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.