This was a triumph for Newcastle and another fiasco from Manchester United. Maybe soon Erik ten Hag will have a real problem of job security, because, after declaring himself confident that he and his players could revive their season after Sunday’s 3-0 humiliation here by Manchester City, continuing their Carabao Cup defence was a prerequisite. Be knocked out by Newcastle and the vultures would circle over the manager despite Eddie Howe’s side having downed City in the previous round. Yet this is precisely what occurred on a night when all the goals conceded by United were self-inflicted and spoke of a cohesion and confidence paucity. From the moment Miguel Almirón struck the opener Ten Hag was a man marooned in the technical area, hoping, rather than able, to affect his side. If last season was a triumph of overachievement in finishing third, reaching the FA Cup final and winning this competition, this term is in a rapid reverse the Dutchman has to halt soon. A second consecutive 3-0 defeat at home unwantedly bridged the gap to October 1962 and the last time this occurred, while five defeats from United’s opening 10 matches at their ground has not happened since 1930. There were seven changes for United and eight for Newcastle as Ten Hag and Howe each asked a swathe of second-stringers to come in and do the business. For Ten Hag this was more of a gamble because of his side’s travails. From a glass half-full aspect one loss in the last four was acceptable but Sunday’s capitulation plus his players suggesting they are yet to comprehend their manager’s gameplan had him entering the phase that has come to all post-Sir Alex Ferguson managers: the questioning of his smarts. Newcastle had to overcome the early loss of Matt Targett, who lined up to the left of Anthony Gordon in attack and was replaced by Almirón. They did: thudding the ball about between them, mixing up short and long range passing, as Gordon looked to peel off Victor Lindelöf when, say, Tino Livramento punted a high ball in from the back. Newcastle’s 7,000-plus travelling support were in ear-splitting voice, not quietened even when Casemiro took aim and Martin Dubravka saved. This was a rare foray for United fans to cheer as subsequently Joe Willock claimed a free-kick, Joelinton dominated midfield, and Hannibal Mejbri and Casemiro were each booked. Every time the home team went forward an errant touch from Mason Mount or Alejandro Garnacho stymied them. And, from such play, they were sucker-punched. Garnacho – again – lost the ball on his left wing. Livramento collected and ghosted past Mejbri and Mount and turned the ball across to Almirón: a sluggish Diogo Dalot could do nothing and the substitute found the inside of André Onana’s left side-netting. “You’re getting sacked in the morning,” Ten Hag was jubilantly informed by Newcastle’s crowd, whose mood soon skyrocketed further. The second goal was as embarrassing as the first for United, because Almirón made total mugs of Casemiro and Dalot by clipping possession between them to Willock. The latter crossed from the left, the ball came to Lewis Hall and he arrowed his volley in. So at the break Ten Hag’s men were as disjointed as they were at the finish on Sunday, each strike a calamity of defending. They walked off to the echoes of Newcastle supporters’ “Olés” that marked their side tapping the ball about, and serial boos from their own contingent. Ten Hag’s move for the second half was to change Casemiro and Dalot for Sofyan Amrabat and Aaron Wan-Bissaka, ignoring, for the moment, Bruno Fernandes, Marcus Rashford and Rasmus Højlund, who were also on the bench. A razor-sharp sequence that featured Antony and Wan-Bissaka and ended with the latter’s ball in was the best yet from United. Could they, then, apply any pressure? The answer, for a while, was a resounding yes. Sergio Reguilón, Garnacho, and Mount probed along the left channel. Harry Maguire pirouetted gracefully near goal to set up an attack that had United flowing along the same wing but when Amrabat pulled the trigger, following a Mount dink in, he misfired. A give-and-go between Antony had the Brazilian blazing over and clutching his head but United were, finally, in the game. It did not last. Again, this was self-inflicted folly. Amrabat was dispossessed by Joelinton and the ball was spun to Willock, who danced through as United backed off and rolled the finish in from distance, Onana again soundly beaten. Now, surely too late, Ten Hag called for Højlund, Rashford and Fernandes. “We’re going to Wembley,” sang delirious Newcastle fans. Ten Hag has to get back to the drawing board – and successfully. If not, his position may be under threat, as underlined by the thousands of seats vacated before the end.