The game was effectively decided by two key talking points which split opinion on both sides of the Mancunian divide as Phil Foden was sent off on 23 minutes and Erling Haaland clinched the result on the hour mark.
Foden was shown a straight red card by referee Michael Oliver - for kicking out at United captain Bruno Fernandes - and controversy reigned over Haaland's winner as refereeing body Pro Ref admitted it should have been ruled out for offside.
The call to dismiss Foden was a bold one from Oliver, as Fernandes initially looked to have kicked the England international, and former Liverpool star Danny Murphy believes a yellow card each would have been the correct resolution.
"Nobody would've batted an eye line if they both got a yellow card and a telling off for silly petulance and stupid kick outs.
"Fernandes gives Foden a little nudge with his foot while he's on the floor, but Foden's foot is high, which gives the referee the idea to send him off.
"But, in a game like this, players know they are taking risks with those types of challenges."