Ten Hag's side were blown away by West Ham's late strikes at the London Stadium, condemning them to an eighth Premier League loss already this season.
United, languishing in eighth place, have managed just one win in seven games in all competitions.
They have lost three of their last four matches and failed to score in any of them for the first time since 1992.
It is another bitter blow for Ten Hag, whose increasingly tenuous hold on his job will surely be the first thing for Jim Ratcliffe to resolve when the British billionaire finally completes the purchase of 25 percent of the club.
Ratcliffe is reportedly set to take control of United's football operations as part of the deal with the American owners and he will arrive at Old Trafford to find the club at one of the lowest ebbs in its illustrious history.
It has been a wretched second season for Ten Hag, whose team have been eliminated from Europe after finishing bottom of their Champions League group, while also crashing out of the League Cup.
Ten Hag believes United can "change the story" once key players return from injury.
But this pitiful surrender against a team thrashed 5-1 by Liverpool's reserves in the League Cup quarter-finals on Wednesday underlined the depths United have sunk to under the beleaguered Dutchman.
After serving guests raw chicken last month, the local council this week confirmed that United's food hygiene rating has been slashed from five to one.
The unfortunate diners aren't the only ones connected with United to be left with a queasy feeling this season.
United have lost 13 games in all competitions this season -- their most defeats before Christmas since 1930-31 when they finished bottom of the table.
Arresting their steep decline looks beyond Ten Hag at present.
United in disarray
With Diogo Dalot, Harry Maguire Victor Lindelof and Raphael Varane all absent, 19-year-old Willy Kambwala made his United debut in central defence.
West Ham were quick to test United's raw French youngster as Emerson advanced for a low strike that forced Andre Onana into a save.
Marcus Rashford was left on the bench for a second successive game after scoring just two league goals this season, but United's lacklustre attack was hardly improved by his exile.
Bereft of rhythm and confidence, Ten Hag's men laboured to establish even a semblance of momentum as they failed to build on last weekend's gritty draw at Liverpool.
It took United over half an hour to muster a shot on target when Antony's tame effort was easily held by Alphonse Areola.
Alejandro Garnacho, one of three teenagers in United's line-up, squandered a golden opportunity to break the deadlock with a weak shot straight at Areola from close-range.
Just back from suspension, United captain Bruno Fernandes showed his much-criticised reckless nature again as he needlessly earned a booking for swiping at Kudus.
Onana kept United on level terms with a superb tip-over to repel Bowen's header.
Rashford came on for the anonymous Rasmus Hojlund after 56 minutes, extending the Danish striker's disappointing run in his debut season.
When Fernandes sent a wayward effort high into the stands, the murmurs of discontent were growing among United's travelling fans.
Lucas Paqueta's sublime chipped pass prised open the United defence and Bowen made a perfectly timed run to beat the offside trap before scrambling his shot past Onana for his 11th league goal this term.
United were in disarray and Kudus delivered the knockout blow six minutes later.
Encapsulating their dreadful display, Kobbie Mainoo carelessly conceded possession and Kudus accelerated clear to drill a low strike past Onana from the edge of the area.
Source: France 24
BDST: 2149 HRS, DEC 23, 2023
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