Erling Haaland and Phil Foden scored hat tricks Sunday as Erik ten Hag was humiliated in his first Manchester derby.
Manchester City destroyed rival Manchester United 6-3 at the Etihad and moved to within a point of Premier League leader Arsenal.
It was Haaland's third hat trick of the season – and his third in successive home league games.
Ten Hag becomes the sixth United manager since Alex Ferguson's retirement to lose his first derby – but had a heavier defeat than either David Moyes or Ralf Rangnick, who both lost by margins of 4-1.
The Dutchman came into the game having been named manager of the month in the Premier League but any celebrations were short-lived after a traumatic afternoon for United in the highest-ever scoring meeting between these teams.
It was a case of damage limitation at the halftime interval after City raced to a 4-0 lead in an utterly dominant display.
Pep Guardiola's team controlled 62 per cent of possession by the midway point and was ahead after just eight minutes through Foden.
United had already survived one goal-mouth scramble in the opening moments by way of warning of what was to come.
Haaland struck twice in the space of three minutes later in the half, and then set up Foden for the midfielder's second just before halftime.
A number of empty seats appeared in the away section of the crowd, with many United fans failing to show for the second half.
Those that did stay witnessed United's Antony score a wonderful goal from distance after 56 minutes.
But City was soon dominating again, with Haaland completing his treble and then setting up Foden to do likewise.
Substitute, Anthony Martial, scored twice in the last 10 minutes – the second from the penalty spot – but the humbling had been complete long before.