Peter Schmeichel tore into three of Manchester United's defenders as he admitted Manchester City deserved to score far more than two goals in their derby triumph.
City cruised to victory at Old Trafford on Saturday afternoon after Eric Bailly scored a calamitous own-goal and Bernardo Silva struck just before half-time.
Silva capitalised on disastrous defending from Harry Maguire and Luke Shaw to find the back of the net from close range with some help from David de Gea.
Instead of knocking the ball behind for a corner, Maguire and Shaw allowed Joao Cancelo's cross to find the City forward unmarked at the back post.
Schmeichel blasted the duo for their failure to clear their lines in a despairing verdict on his former club.
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"The second goal was a terrible goal to concede," the former goalkeeper told BBC Radio 5 Live. "David de Gea couldn't do anything initially, but my God, what are Harry Maguire and Luke Shaw doing on the back post?
"They should clear the ball. Maguire and Shaw both leave it, they both have the chance to clear it, thinking that either the keeper is coming out for it or that it's going out for a corner. Oh my God!
"David de Gea couldn't do anything about the second goal, it should have been cleared. The defending, I mean…"
City were utterly dominant against their local rivals, with over two-thirds of possession and 16 shots compared to their hosts' five.
"Man City have been far, far superior and it could have been four," Schmeichel added. "There's a lack of willingness to do what you have to do - closing down, stop the crosses, the passes, it's not happened."
Schmeichel was particularly disappointed with Bailly's performance, especially as the Ivorian centre-back was impressive against Atalanta in the Champions League four days earlier.
He said: "We talked about this pre-game - what version of Eric Bailly will turn up today?
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"He got away with a couple of similar situations on Tuesday, this time he didn't. To allow City to get the cross in when you have seven players in the box is not good enough.
"Two players at the back post could have scored if Bailly didn't touch that anyway, but Bailly should have easily cleared that for a corner."
United have slipped to sixth in the Premier League table and return to action against Watford after the international break.