By SABC Sport
9th December 2023
The Red Devils were embarrassed by Andoni Iraola's ever-improving Cherries just three days on from beating Chelsea with arguably their best performance of the season.
Star turn Dominic Solanke scored a smart fifth-minute opener and hit the post in an alarming first-half display by United that was followed by a complete capitulation after the break.
Substitute Philip Billing headed Bournemouth further ahead and Marcos Senesi added another from a corner in front of the elated, open-mouthed away support.
A number of United fans left after the third and a VAR review prevented Dango Ouattara adding another on an afternoon that ended with widespread boos from the Old Trafford faithful.
This result is sure to heap pressure on boss Ten Hag, whose decision to replace Anthony Martial with Rasmus Hojlund was cheered on a dark day that could soon be compounded.
United's European ambitions are hanging by a thread heading into Tuesday's final Champions League group game at home to Bayern Munich. A trip to high-flying rivals Liverpool follows next weekend.
The 11th loss in all competition of the campaign - and 18th of 2023 - was on the cards from the outset.
United stumbled out of the blocks and were breathing a sigh of relief when Solanke went down in the box as Andre Onana attempted to reach a back pass with 46 seconds on the clock.
The VAR decided against awarding a penalty after reviewing the incident, but the hosts' sloppiness was quickly punished.
Having won the ball and kept it smartly, Bruno Fernandes' clipped ball from deep on the left side of their own half was picked off by Lewis Cook.
The Cherries midfielder nipped in ahead of Scott McTominay, burst forward and sent a low ball that Solanke smartly took past Onana with a delicate six-yard finish.
United were stunned and quickly looked to make amends, but Harry Maguires looping header was the best they could muster despite controlling possession.
Bournemouth were as defensively organised as they were committed and threatened to land another first-half blow on several occasions.
Marcus Tavernier saw a low attempt saved and found the net in the 24th minute, turning in from close range after Onana stopped a header from what proved to be an offside Solanke.
Illia Zabarnyi saw an effort from a corner turned around the post by Diogo Dalot as the away side pushed for another, going onto hit the woodwork as half-time approached.
McTominay saw a first-time pass cut out and Solanke was slipped in to get away a low shot that beat Onana but came back off the far post.
The striker would have got away another in stoppage-time was it not for a key Maguire challenge at the end of a Bournemouth break. Little wonder there were boos at the interval.
The lack of United changes at half-time was more surprising and there were huge cheers when Hojlund replaced ineffective Martial in the 56th minute.
There had been groans during the forward's involvement towards the end of the opening period and Ten Hag gave him a pat on the back after traipsing around the pitch to the dugout.
Hojlund was swiftly booked for waving an imaginary card and soon expressed more frustration when Dalot struck into the side-netting rather than crossing.
The hosts' mood soon worsened. Bournemouth won possession and Solanke darted forwards, before playing wide for Tavernier to lift a cross to the far post where the towering Billing headed home.
The 68th-minute goal was followed by a another in the 73rd and led to some of the 72,427 in attendance making an early exit.
Tavernier's corner from the right was good but made to look a lot better by awful defending, with Senesi all too easily able to get away a header that beat Onana.
Ten Hag made a triple change but it was too little, too late.
As if the afternoon was not damaging enough, Fernandes' moaning at the referee earned him a a booking that rules him out of next Sunday's trip to Liverpool.
The VAR saved United from conceding a fourth in stoppage-time, with Ouattara adjudged to have handled when bundling past the hapless hosts.