The teenage midfielder – whose only prior appearance for Newcastle came in the Carabao Cup in August – picked out the bottom corner midway through the second half to settle a closely-fought encounter and lift Steve Bruce’s side out of the relegation zone.

Lining up alongside his elder sibling, Sean, Longstaff nearly opened the scoring in the first half, seeing a rasping right-footed effort from a similar distance drop onto the woodwork.

A poor Man United side only fashioned one clear-cut chance across the 90 minutes – spurned by Harry Maguire just before the interval – and offered little after falling behind.

Smarting from last week’s thumping defeat to Leicester City, Newcastle got off to a purposeful start at a rain-soaked St. James’. Within 40 seconds, Red Devils skipper Ashley Young was forced into a crucial challenge to divert Miguel Almirón’s dangerous centre out for a corner, Allan Saint-Maximin having instigated the move with a marauding run. Two minutes later, Fabian Schär struck the wall with a 25-yard free kick, before wide-man Saint-Maximin drilled off-target after skipping betwen two Man United defenders.

Ole Gunnar Solskjær’s side started to get a foothold after that, but – out of nothing – the Magpies almost took the lead just before the half hour mark. Saint-Maximin teed up the younger Longstaff 20 yards out, who took a touch to set himself before clipping the crossbar with a beautifully-struck shot. Longstaff yelled and clapped his hands together in frustration, with visiting stopper David de Gea almost certainly not getting to it.

It was Longstaff’s older brother, Sean, who created the Magpies’ other big chance of the half. He picked out Miguel Almirón’s run from deep, the Paraguayan just about holding his line to find himself one on one with de Gea. But Almirón dawdled, allowing Maguire the chance to sprint back and get in the way of a left-footed effort.

And yet, it was Man United who ought to have gone into the interval a goal in front. With 44 minutes on the clock, and Schär having gone perilously close to heading the ball into his own net to afford the Red Devils the chance, Maguire somehow nodded Ashley Young’s corner from the left down and wide of the upright from a completely unmarked position.

Maguire got his head to another corner shortly after the break as the visitors started the second half in a slightly more assured fashion than they did the first. Scott McTominay saw a right-footed shot blocked just after the hour mark before Martin Dúbravka clawed away another Young set-piece.

Newcastle’s first opportunity after the interval fell to Andy Carroll, who took over Joelinton’s role up top. The towering frontman got his head to Matty Longstaff’s in-swinging cross after 65 minutes but cleared the crossbar from eight yards.

With the game starting to open up, Swiss defender Schär made two vital interventions at the opposite end, blocking a low strike from Young deep inside the area before getting a crucial toe to a menacing cross from the right to deny Marcus Rashford a tap-in.

A goal, from somewhere, appeared to be coming, and sure enough – on 72 minutes – it did. Saint-Maximin – arguably the most threatening player on the pitch on the day – again played a key role by advancing with the ball and taking a couple of Man United defenders with him. He picked out Jetro Willems, who cut the ball back for Matty Longstaff. The Gallowgate End opened up for the Magpies’ rookie midfielder, and de Gea was powerless to stop his low-struck effort from just outside the penalty area from hitting the back of the net.