Until Soungoutou Magassa’s 83rd-minute equaliser Manchester United seemed to be flowering in the cold of winter on the way to a win that would have been their fifth in eight games.

Instead Jarrod Bowen’s flick-on from Andy Irving’s corner from the right had to be cleared off the line by Noussair Mazraoui, only for the ball to go straight to Magassa, who drove home a first goal for the Hammers.

United had not been a fluid picture of poetry in motion yet their display featured enough high-octane moves to suggest they are improving and they appeared to have scored the winner through Diogo Dalot. Instead, questions about their solidity remain because West Ham had rarely threatened until their hosts switched off and were punished.

The Irving corner came when Leny Yoro, on as a substitute after being dropped, missed a clearing header. Then Bowen was left unmarked by Bruno Fernandes. As Bowen said: “Not many people pick me up in the air. I’m 5ft 9in or something like that, so not the tallest.”

They were two material errors that can augur sourly for United and which left Ruben Amorim upset. “Angry and frustrated, that’s it,” said the Portuguese. “We are really inconsistent but if you look at the goal [conceded], we have a long ball, we have everything under control, [so] we need to do better.

“The game was in control. We knew it, [so] let’s defend far from the box. We knew set pieces would be a problem with the difference in height in the team but we could do it. We could maintain the ball after the first goal and again we lost two points.”

Amorim was pressed if he had given the players a dressing-room rollicking. “In that regard I am almost always consistent [calm]. I had one [such incident] after Brighton last year [a 3-1 loss]. I will talk to them tomorrow [Friday],” he said.

Ten points and nine places separated the teams at the start. West Ham, in 18th with 11 points after 13 games, were bidding to become only the ninth side to survive with that tally (or lower) at this juncture. United’s 21 points had Amorim’s men only two behind fifth place that may be sufficient for a Champions League berth, which, despite the manager downplaying the notion, is a target.

Jab and counter-jab was the pattern in early exchanges that featured Amad Diallo and Fernandes both going down in the Hammers area and having penalty shouts rejected by the referee Andrew Kitchen.

Amorim’s surprise selection was in central defence where Ayden Heaven, 19, was in for Yoro and a concerning start featured a seventh-minute yellow card and him being turned twice by the 33-year-old Callum Wilson.

Better for United was Diallo’s dart down the right. The wingback’s cross was kneed goalwards by Joshua Zirkzee, Aaron Wan-Bissaka cleared off the line, Matheus Cunha’s overhead stab was repelled before Fernandes sprayed a scissor-kick wide.

While Amorim’s other changes were Cunha for Mason Mount and Mazraoui for Matthijs de Ligt, Lucas Paquetá’s silly sending-off against Liverpool meant Tomas Soucek was drafted in by Nuno Espírito Santo. If he had taken a fall when Diallo clipped him near the break, Kitchen might have awarded a spot-kick.