It was a harsh call, but Monreal made amends in the 53rd minute, masterfully steering Mesut Ozil's cross back across goal for Theo Walcott to restore Arsenal's lead with a rare header.
15 minūtes pirms pamatlaika beigām Svonsī futbolisti atradās vadībā ar 3:1, bet "Crystal Palace" deviņu minūšu laikā guva trīs bezatbildes vārtus, panākot vadību sev.