blonska63: Maglie Bayern Monaco
Maglie Bayern Monaco
Kevin De Bruyne hit a first-half double, either side of Jadon Sancho's curled response, as United's backline were punished for their disorderly defending.
Riyad Mahrez then struck a brace of his own in the second period to compound United's woes and shift the spotlight from Ronaldo to United's ragged defence.
While United showed signs of promise in attack during the first half in particular, chaotic scenes in their own penalty then saw City ruthlessly put their neighbours to the sword.
De Bruyne's second strike in particular left United's back four sprawling, with Victor Lindelof sucked out of position by Phil Foden and his three defensive comrades left on the turf as the Belgian tucked home following a scramble.
Speaking to Sky Sports at half time, former United captain Roy Keane lambasted Rangnick's defence for their notable lack of application and organisation.
Question marks will remain over Ronaldo's future, but United's need to address their extortionate yet leaky backline must be the priority.