United’s campaign is unravelling fast and this humiliating, shambolic defeat at the hands of a vibrant Crystal Palace the latest painful demonstration of their flaws.

Ten Hag’s side were utterly exposed by Oliver Glasner’s much improved Palace side with Michael Olisee in particular outstanding. The winger tormented a dishevelled, disorganised United, scoring twice, with Jean-Philippe Mateta and Tyrick Mitchell also on target for the home side.

It was a painful watch for the United manager whose side have now won just one of their last six games and are in serious danger of missing out on European football. The nature of this loss will have caused alarm to Sir Jim Ratcliffe, the co-owner, as he plots a course for next season. Alarmingly from United’s point of view, the scoreline could have been even more one-sided.

In Ten Hag’s defence, he had once again been forced to reshape his team after injuries ruled out Harry Maguire and Bruno Fernandes. The absence of Maguire meant Jonny Evans was the only senior centre-back still standing. Short on options, Ten Hag opted to pair Casemiro with the Northern Ireland international, his 14th different centre-back combination in the Premier League this season. It came as little surprise then, that the cracks soon began to show.

The visitors’s weaknesses were brutally exposed when Olise fired Palace into a 12th minute lead. The Palace winger collected a throw-in 40 yards from goal, easily side-stepped Casemiro who had been drawn into his more familiar midfield possession and simply ran unchallenged into the space vacated by the Brazilian before placing a left foot shot across Andre Onana.

The goal exposed United’s defensive weaknesses and certainly wasn’t the last time Casemiro was guilty of losing his bearings. At times Evans could be seen screaming and pointing at his partner while trying to cover two positions at once.

It could have got worse for Ten Hag’s side when Daniel Munoz, the Palace right-back, played the ball inside to Olise who saw his goal-bound shot blocked by teammate Mateta midway through the first half. Moments later a poor back pass from Kobbie Mainoo almost let Olise in again with Onana just able to recover the situation by diving bravely at the Palace winger’s feet.

United were creaking every time they were put under pressure and it came as no surprise that Palace were able to double their lead before half-time. It also came as no surprise that Casemiro was at fault in the build up to the goal.

Once again the Brazil international got drawn out of position, this time finding himself moonlighting at right-back near the halfway line when he conceded possession. That allowed the Mateta a direct run at Evans and the in-form forward easily side-stepped the United centre-back before racing into the box and beating Onana with a powerful left foot shot. The look of despair on Ten Hag’s face as he sat back down in the dug out told its own story.

The Dutchman’s mood wasn’t helped by the decision to disallow Casemiro’s header that would have brought United level midway through the first half after a rare United attack. A Christian Eriksen free-kick was deflected over the bar and from the corner, Casemiro looped a far post header into the goal, only for referee Jarred Gillett to rule that Rasmus Hojlund fouled Palace keeper Dean Henderson.

Ten Hag sent his players back out early at the start of the second half but it made little difference. Antony did finally manage to produce United’s first effort on target but there was little doubt the momentum was still with Palace who were visibly growing in confidence.

Eberechi Eze tested Onana with a first time shot and then fired narrowly wide after being set up by a neat flick from Olise. Onana was then forced to save from Mitchell and Will Hughes in quick succession, adding to the sense a third goal was imminent.

It came in the 58th minute after a short-corner was only half cleared, allowing Adam Wharton to deliver the ball into the far post where United right-back Diogo Dalot, under pressure from Joachim Andersen, could only play the back across goal where Mitchell finished from close range. Ten Hag complained Dalot was fouled but the main problem lay with his side’s inability to deal effectively with the ball into the box.

United were falling apart and worse was to come when Casemiro once again had a moment to forget in the 66th minute when he was robbed by Munoz close to the byline. The full-back pulled the back towards Olise who produced the moment of the match when he arrowed in a left foot shot that flew past Onana.

Crystal Palace (3-4-3): Henderson 6; Clyne 7 (Guéhi 78, 6), Andersen 8, Richards 7; Munoz 7, Hughes 7 (Riedewald 67, 6), Wharton 8, Mitchell 7; Olise 9 (Schlupp 85, 6), Mateta 8 (Edouard 68, 6), Eze 8 (Ayew 85, 6).

Subs: Matthews, Ward, Ahamada, Rak-Sakyi.

Manchester United (4-2-3-1): Onana 7; Dalot 5, Casemiro 3, Evans 6, Wan-Bissaka 6; Mainoo 6, Eriksen 5; Antony 4 (Amrabat 60, 6), Mount 6 (Diallo 80, 6), Garnacho 5; Hojlund 5 (Wheatley 84, 6).

Subs: Bayindir, Heaton, Collyer, Amass, Ogunneye, Jackson.

Referee: J Gillett 6