Gary Neville has urged Mikel Arteta to follow Sir Alex Ferguson's tactic and sign "ice-cold" defenders.
Arsenal's defence has been a problem area for the club in recent seasons and cost them again last week.
David Luiz made two glaring errors against Man City, resulting in Arsenal going two down and The Brazilian receiving his marching orders having only been on the field 25 minutes.
The jury is still out on his centre-back colleagues too, with Shkodran Mustafi often the target for criticism from Gunners fans, while Sokratis has not convinced during his time in north London.
And Neville feels Arteta needs to take a leaf out of Fergie's book at United if he wants to stamp out the mistakes from his back line.(Image: Arsenal FC via Getty Images)
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"They just need defenders with better concentration," Neville said on his podcast. "There were elements of me that were emotional when I was a player Sir Alex Ferguson would knock it right out of me.
"He always said I hate emotional defenders. He thought defenders have to be ice-cold. You are gonna make mistakes as a goalkeeper and a defender.
"But it's the second mistake where you try to win it back and you give away a penalty. It's where you try and win it and you can't win it."
Luiz's future at Arsenal has come under particular scrutiny after the City match as he gave away another penalty, having already done the same at Liverpool and Chelsea this season.
Such errors were few and far between during Neville's time at United, with the likes of Rio Ferdinand and Nemanja Vidic rarely putting a foot wrong.
Neville continued: "You've got to put away your ego when you're a defender. Delaying helps because your team-mates come back.
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"You get too many defenders who try and win the first ball and try to dive in, and we've seen that with Arsenal's defenders over the years.
"David Luiz, [Shkodran] Mustafi, Sokratis [Papastathopoulos] when he plays, they like to challenge when they don't have to challenge.
"They feel like they have to win the ball, and sometimes it isn't there to win."
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