Arsenal were dealt a major blow to their Premier League top four hopes as they succumbed to a 2-3 loss to Crystal Palace at the Emirates on Sunday.The Gunners had the ultimate opportunity to move ahead of Tottenham Hotspur after the North London rivals dropped points against Manchester City on Saturday. However, the loss now means Chelsea could go above them if they avoid defeat against Burnley later tonight.Both Mesut Ozil and Pierre-Emerick Aubameyang found the back of the net but Arsenal's defensive shortcomings helped the visitors to take full advantage and establish a win.Shkodran Mustafi’s mistake that allowed Wilfried Zaha to score Palace's second goal has particularly gotten the Gunners brigade riled up.When asked about the German's performance, Arsenal boss Unai Emery refused to criticise, saying (via The Standard), "He has been consistent.""They [Crystal Palace] have very good players. Secondly at set-pieces we didn't work and be strong like we are doing all season.""We can speak to players usually and they can play very well, sometimes not play with due diligence, but I prefer to speak about consistency throughout the season.""Every player is helping and playing with big performances but, today, defending against Benteke and Zaha you can suffer more.""If today, we were better at set pieces maybe we could win this match. Also, we controlled the possession but they defended well. We didn't find the best situation to score."Fans believe that Emery himself was partly to blame for making seven changes to the first team in what has been deemed to be an under-estimation of their visitors.Mustafi, who has put unconvincing performances all season, has now come under fire on social media as fans take to Twitter to address his performance:Goodnight to everyone except Shkodran Mustafi.— FK ☕️ (@fkhanage) April 21, 2019Arsenal, you win, you go 3rdMustafi: pic.twitter.com/97MPkFEWW3— Mr Sam (@XammyOfficial) April 21, 2019mustafi is so bad he broke the drake curse pic.twitter.com/nN4sguxXOz— Billie (@Billie_T) April 21, 2019Here is a compilation of Mustafi best moments at Arsenal...Enjoy 😁. #ARSCRY pic.twitter.com/PbEVDtNHq3— Sports News (@FIFAWCGoals) April 21, 2019Gabriel was never as bad as Mustafi ... Valencia hit the jackpot— Memżdoużi (@Durchiga) April 21, 2019Jokes aside if Mustafi is in our squad next season, you will have to question the ambition of the club. He is on 90kpw and almost costs us every match he starts. He isn't good enough for a top half PL team.Same goes with Jenkinson and Elneny. Not good enough to start for us.— P™ (@Cechque) April 21, 2019Thread on every Mustafi error that has cost us in games. pic.twitter.com/UI9UZp9HNO— Ali (@AFCAlii) April 21, 2019Emery has said in his press conference that Mustafi has been consistent all season, he’s 100% correct, he’s been consistently SH*T!!!— MR DT © (@MrDtAFC) April 21, 2019I've seen plenty of shit defenders at Arsenal what separates Mustafi is his arrogance— El Padrino (@JCourier1) April 21, 2019Shkodran Mustafi is on £90k per week. We paid £35m for this dummy. We were robbed, I'm crying 😢 pic.twitter.com/1KLVWmlDbL— ✗coubar 🍫 (@xcoubar) April 21, 2019Arsenal are unbeaten in premier league games Mustafi and Lichsteiner haven't featured in....— LTArsenal™️ (@ltarsenal) April 21, 2019When we sell Mustafi I am going to hire out Finsbury Park and host a massive rave, everyone is welcome, we can celebrate together.— MR DT © (@MrDtAFC) April 21, 2019If Mustafi is not sold in the summer you have to question the club’s ambition.— Sam (@samuelJayC) April 21, 2019