Manchester United were humiliated as Bournemouth ran riot at Old Trafford on a sobering day for Ruben Amorim.
The result means United will be in the bottom half of the table at Christmas for the first time since the 1989-90 season.
United capitulated in the second half and there were boos from home fans on the final whistle.
Bournemouth went ahead on 29 minutes when Dean Huijsen headed home totally unmarked from a free-kick as United conceded another set-piece goal.
United were poor for the majority of the match but came to life for the short spell at the end of the first half and Bruno Fernandes missed three chances to equalise, while Huijsen was fortunate not to score an own goal from a corner.
Bournemouth doubled their lead on 61 minutes when Noussair Mazraoui made a rash challenge on Justin Kluivert and Kluivert picked himself up to score from the spot.
Dango Ouattara picked out Antoine Semenyo as Bournemouth made it two goals in two minutes when he fired past Andre Onana.