Roy Keane described the Manchester United's display at the Etihad as "unforgivable" after they were on the wrong end of a 4-1 hammering.
Pep Guardiola's side took the lead inside the opening five minutes before Jadon Sancho's delightful equaliser gave the away faithful hope of a surprise win at the home of their local rivals.
Kevin De Bruyne bagged his and City's second just five minutes later before the second-half saw the hosts take the level up a notch to a standard United simply could not deal with.
Riyhad Mahrez also notched a brace but it was the manner in which United appeared to roll over and accept the result that left Keane fuming come full-time.
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Analysing the game on Sky Sports, Keane was scathing in his assessment of his former side.
"The worst thing you can say about Man Utd is that they gave up, in any game to give up is unforgivable really," the United legend fumed.
"The beauty with top level sports is that there is no hiding place, I know United have come here in the last couple years and done well but we saw all of United’s shortcomings today.
"There’s ways to lose football matches, we’ve all lost football matches but the way United lost today – they stopped running, they gave up, players not running back, that’s what I don’t understand."
Keane went on to explain that while attention may shift to interim boss Ralf Rangnick and his methods could come into question, the spotlight should be on the players.
"The manager will get criticised, the tactics but players not running back – it's really unacceptable and they threw the towel in which is shameful.
"It’s hard when you are out there and they are keeping the ball but I’ll go back, you see some of the goals – United players have shown quality down the years but they are reflection of where the team is and where the club is.
"They are so far behind the other teams, there’s ways to lose football matches – there's obviously stuff going on in the dressing room we hear noises of new manager coming in but you’re own bit of pride has to kick in eventually."
Keane went on to claim the efforts of the United players were "shameful" considering the magnitude of the game.
"I’m getting frustrated watching it because I can forgive mistakes but you’ve got to run back, there’s fix or six players that should never play for Man Utd again – shameful, shameful that you can’t run back, can’t put your body on the line.
"Man Utd – a derby match today, sub’s coming on and you’re hoping they’ll have an impact but they're not ready to run around
"City weren’t at their very best, they didn’t have to be at their very best – a bit like the game at Old Trafford, they gave up and shame on them."
