Arsenal have had a week to think about what happened against West Ham. I hope their thought process was something along the lines of "don't be stupid", because that's what cost them two points last weekend. Crystal Palace may not pose as stern a test as West Ham - Palace are currently in 16th place, probably safe but not 100% assured of safety, which means that what looks like a fairly straightforward game could get really interesting really fast if Arsenal are still in brainfart mode.
Arsenal are in the same health they were last week, which...fine? I guess? Anyway, there's no fresh injuries, and hopefully Petr Cech finally regains his spot this week.
Crystal Palace had a game against Everton midweek, which saw Everton go down to 10 men in the 52nd minute before playing Palace to a scoreless draw which didn't really assuage their nerves; while they have a decent cushion over 18th place, they have one win since December, and in that stretch of 16 games have scored 12 goals. So, while they have a lot to play for, they don't have a lot of firepower with which to win it.
Arsenal have enough to win this game; as mentioned, though, they'll need to get out of their own way enough to collect the three points.