If Erik ten Hag’s future at Manchester United remained up for debate then surely this removed any lingering doubts for Sir Jim Ratcliffe. Even amid a season in which his team have lurched from one disaster to another, a scintillating performance from a Crystal Palace side inspired by the magical feet of Michael Olise delivered one of the most embarrassing evenings of the Dutchman’s tenure. United’s European aspirations for next season may now have to rely on them beating Manchester City in the FA Cup final after two goals from Olise, Jean-Philippe Mateta’s ninth in 11 since the appointment of Oliver Glasner and another from Tyrick Mitchell gave Palace a league double over their opponents for the first time in Premier League history. The scant consolation for Ten Hag was that Palace could not find a fifth to match their record victory over United back in December 1972 after the substitute Odsonne Édouard hit a post late on. For reference, that result led to the sacking of the manager, Frank O’Farrell, three days later. Ten Hag should at least make it through to the end of the season but faces a mammoth task to lift his despondent players after this chastening defeat in south London. Palace have now picked up four victories in their last five matches under Glasner and look like a team who don’t want the season to end. But while Gareth Southgate – watching on from the stands at his former club – would have been impressed with Eberechi Eze and pleased to see Marc Guéhi make his return as a substitute as he aims to prove his fitness in time for the Euros after three months out, it was Olise who stole the show. The former Reading forward has opted to play for France Under-21s, although he remains eligible for England. Having now been directly involved in 13 goals in his last nine starts here, the 22-year-old would certainly be under consideration if he ever changes his mind. In the absence of the sidelined Bruno Fernandes and Harry Maguire, the extent of United’s injury list meant that two of the substitutes were goalkeepers and four had never made a senior appearance. Jarred Gillett, the referee, made history by wearing a head-mounted ­RefCam, with ­footage to be broadcast at a later date, and his first decision was to wave away Mitchell’s appeals for a penalty after a challenge from Jonny Evans. It was not long until Palace found a way through United’s porous defence as the familiar failings returned, however. A sublime piece of skill from Olise after he received Daniel Muñoz’s throw-in left Casemiro sprawling in the centre circle as the forward sped away before clipping a precise shot past André Onana from the edge of the penalty area. “Professionals shouldn’t allow this,” was Ten Hag’s verdict. “It’s not the first time this season it has happened.” The electric Olise could have had a hat-trick inside the first 23 minutes had Mateta not blocked his goalbound shot after he was again set up by Muñoz before shooting straight at Onana. The visitors’ hopes of a quick equaliser were dashed when Gillett ruled Rasmus Højlund had impeded Dean Henderson, the former United goalkeeper, as he jumped for the ball. United were fortunate Olise could not capitalise on a slip from Kobbie Mainoo that left him clean through on goal. Onana then almost came unstuck when trying to clear under pressure from Mateta and sliced the ball out of play to the delight of the home fans. But United’s luck could not hold forever and Ten Hag looked on forlornly when Chris Richards fed Mateta after winning possession. The in-form striker powered past the helpless Evans before smashing his shot into the net. United’s players were sent out into the rain early for the second half but Palace continued where they left off as Eze volleyed Nathaniel Clyne’s cross straight at Onana. Casemiro thought he had pulled one back when he stabbed home after his header came back off a post, only to be flagged offside by almost a metre. That only seemed to provoke Palace as a wonderful backheel by Olise through the legs of Casemiro teed up Eze to curl just wide before Mitchell and then Will Hughes were denied by Onana. United were clearly there for the taking and Adam Wharton’s brilliant cross allowed Joachim Andersen to set up Mitchell to tap home from close range. Ten Hag’s response was to replace Antony with Sofyan Amrabat in an attempt to keep the score respectable. But only Casemiro will know why he allowed Muñoz the opportunity to steal the ball near the byline and free Olise to hammer home a fourth. The double substitution of Olise and Eze to a standing ovation ended the torment of United’s defenders for the evening. To their credit, the away supporters kept singing until the bitter end but it remains to be seen if their manager can survive beyond this campaign.