Former Arsenal defender Martin Keown has picked apart every error Shkodran Mustafi made in Crystal Palace's 3-2 win at the Emirates.
According to the retired centre-back, the German was at fault for all three goals as Christian Benteke, James McArthur and Wilfried Zaha put the ball past Bernd Leno.
Mesut Ozil and Pierre-Emerick Aubameyang pulled two goals back for the home team but it wasn't enough as Mustafi made multiple errors, not all of which were exploited by the visitors.
Speaking on BBC Sport's Match of the Day 2 programme, Keown spelled out exactly what the former Valencia defender got wrong in his battles with the Palace goalscorers.
Every moment Shkodran Mustafi has cost Unai Emery this season to show he must leave Arsenal
"This is just poor defending, Mustafi," he said on the opener scored by Benteke, the Belgian striker who had gone 358 days without a Premier League goal prior to the win over Arsenal.
"When the ball goes over your head you drop off as quick as you can. He's not even aware of Benteke.
"If the ball is delivered into the box, it's a tap in. Mustafi has completely switched off.
"He sees him and puts the burners on but Benteke just steps inside of him. It's school boy defending."
Ozil found an equaliser in the 47th minute after half-time only for Zaha to put Palace back in front, and once again Mustafi was to blame.
"Mustafi, good position," said Keown as he looked back over a replay of the goal. The German was initially in the right place at the right time but soon put himself and his team in danger again.
The unacceptable moment that Shkodran Mustafi showed he has no right to a future at Arsenal
"Just drop off and deal with it," said Keown. "He tries to out-strength Zaha. He calls on the goalkeeper to come but there's no pace on the ball.
"Better decision making. It's costing you and your team. It's avoidable."
MOTD2 then turned to another passage of play that almost saw Palace score again with a loose ball spilling out to the left flank with Mohamed Elneny uncertain as to whether he should go and challenge for it.
In the middle of the picture, strolling through the centre circle of the pitch, Mustafi could be seen well out of position and in no hurry to get back.
"He's arguing," said Keown. "Mustafi's got his hands in the air. The ref is not blowing. Get back and defend!
"Thankfully Ainsley Maitland-Niles has got that in his DNA and he got back to defend."
Arsenal fans cannot believe Unai Emery's claims about Shkodran Mustafi after Palace defeat
In the final clip, Keown turned his attention to the defending for the corner that saw McArthur score Palace's third.
"I'm going to come for Mustafi again," he said. "McArthur is coming in at the far post. You just need to stay with him.
"When everyone else attacks the ball, do your job. Ball comes into the box. Flicks it on.
"Mustafi loses his man and McArthur it's an easy header."
'He'll cost us top four!' - Shkodran Mustafi hammered by Arsenal fans for Crystal Palace display
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