The Red Devils have had big problems defending set pieces this season, with only Wolverhampton Wanderers conceding more goals from set-piece situations in the Premier League this term, and Bournemouth made the breakthrough through that avenue, as Dean Huijsen headed a delivery from Ryan Christie into the back of the net.
It was the sixth successive match that the Red Devils had fallen 1-0 behind, and it became 2-0 just past the hour, with Justin Kluivert scoring from the penalty spot after being brought to the ground by Noussair Mazraoui inside the box.
Man United then conceded a third in the 63rd minute when Dango Ouattara's cross was slotted home by Antoine Semenyo. and it was no more than Bournemouth deserved, with the Cherries the dominant outfit.
The result has left Ruben Amorim's side in 13th spot in the Premier League table, nine points behind fourth-placed Nottingham Forest, while Bournemouth are fifth, just three points off the Champions League spots.
SPORTS MOLE'S VERDICT
The honeymoon period for Amorim did not last long.
Man United have been poor on too many occasions this season, but this performance was right up there in terms of underwhelming displays from the 20-time English champions, with Bournemouth simply too classy for the hosts.
The Red Devils have now lost three of their last four Premier League matches and sit down in 13th spot in the table, eight points off the top four, but they do not deserve to be mentioned as potential challengers for a Champions League spot.
It is a squad that simply is not good enough, and a huge clear-out is needed, but Amorim would have known that already.
Man United's only hope of securing Champions League football for next season is through winning the Europa League, but not too many teams will fear them in that competition based on this viewing.
As for Bournemouth, the Cherries, who have an incredibly talented head coach in the shape of Andoni Iraola, are up in fifth spot in the table, three points behind fourth-placed Forest.
Only one team at Old Trafford on Sunday afternoon looked even slightly capable of making a push for the European spots this term, and it was not the hosts, who were beaten for the seventh time in 17 league games this season.
MAN UNITED VS. BOURNEMOUTH HIGHLIGHTS
29th min: Man United 0-1 Bournemouth (Dean Huijsen)
Bournemouth make the breakthrough in the 29th minute of the clash at Old Trafford, as Huijsen heads a free kick from Christie into the back of the net - the Red Devils once again concede from a set piece.
61st min: Man United 0-2 Bournemouth (Kluivert)
Bournemouth double their lead in the 61st minute of the contest, as Kluivert scores from the penalty spot; Mazraoui fouled Kluivert, and the Cherries attacker rose to his feet before finding the back of the net.
64th min: Man United 0-3 Bournemouth (Semenyo)
Man United concede a third in the 64th minute of the contest, with Semenyo turning a cross from Ouattara into the back of the net from inside the box - game over, and it is another horror show for the 20-time English champions.
MAN OF THE MATCH - ANTOINE SEMENYO
Man United's attackers underwhelmed, with the star forward on the pitch proving to be Semenyo; the 24-year-old was too fast, too strong and too skilful for the hosts, and he deserved to be on the winning side.
Semenyo got his goal in the second period, but he was a huge threat all afternoon, having four shots in total and completing two successful dribbles, with Man United simply unable to contain the talented forward.
MAN UNITED VS. BOURNEMOUTH MATCH STATS
Possession: Man United 60%-40% Bournemouth
Shots: Man United 23-10 Bournemouth
Shots on target: Man United 7-5 Bournemouth
Corners: Man United 13-1 Bournemouth
Fouls: Man United 11-11 Bournemouth
BEST STATS
WHAT NEXT?
Both teams will continue their Premier League campaigns on Boxing Day, with Man United heading to Molineux to tackle Wolverhampton Wanderers, while Bournemouth will welcome Crystal Palace to the Vitality Stadium.
Man United will be aiming to record just a seventh league success of the campaign when they visit Wolves, while Bournemouth will be looking to secure a ninth league victory of the season in their next contest.
Written by
Matt Law