The crushing defeat will lead to renewed calls for Arsene Wenger to consider his future in the Gunners’ hot-seat.
Andros Townsend scored in the 17th minute to put his side in a deserved lead.
The hosts’ performance improved further in the second half, and though Arsenal dominated possession, it wasn’t enough to prevent a second goal for Palace in the 63rd minute by Yohan Cabaye.
A penalty was awarded to Palace not long afterwards, after Townsend was brought down in the box by Emiliano Martinez, though some thought contact was made after Townsend started to fall.
Nonetheless Luka Milivojevic converted the penalty to shore up Palace six points above the drop zone.