This was one of the rare occasions when Man United were able to dominate possession and win – in fact, just the second time in 18 league matches – but there remains work to do, with the defence high among the priorities.

Longstaff scored the winner on a dream top-flight debut against Solskjaer’s men in October and was able to open the scoring at Old Trafford, extending a club-record run without a Premier League clean sheet to a 14th match.

Yet that soft underbelly did not cost Man United this time as Martial struck a quickfire leveller, which 18-year-old Mason Greenwood added to emphatically before Rashford headed home a third as half-time approached.

An undercooked backpass from Sean Longstaff allowed Martial to add another early in a second period in which the France forward hit the post and half-time introduction Paul Pogba stepped up his return from an ankle injury.

This comprehensive win did not start comfortably for Solskjaer’s men.

Miguel Almiron was the first to have an attempt and the hosts’ backline breathed a sigh of relief when Dwight Gayle lashed over after Joelinton was somehow allowed to prod through.

Greenwood was dispossessed on the right flank inside Newcastle’s half for that attempt – just as Fred would be in the 17th minute.

The Magpies broke forwards and Matty Longstaff lifted the ball to Joelinton, who manfully dealt with Harry Maguire and laid back for the midfielder to take a touch and send a shot into the bottom left-hand corner.

Newcastle’s impressive travelling support erupted, but their side were unable to build on the opener.

Sharp build-up play down the left led Luke Shaw to play into Andreas Pereira, whose smart first-time lay-off was greeted by a Martial strike that beat Martin Dubravka at his near post to the relief of the Old Trafford faithful.

Pereira and Rashford had attempts soon after, with the latter bellowing at Greenwood when the 18-year-old gobbled up a wayward Fabian Schar pass. But the teenager ignored him and unleashed a sensational left-footed strike that went in off the underside of the bar via a slight touch off Federico Fernandez.

Solskjaer’s side now had the bit between their teeth.

Pereira saw a free-kick clawed away by Dubravka, who would be beaten in the 41st minute as Rashford leapt brilliantly to head home a clipped Aaron Wan-Bissaka cross. Newcastle’s angry claims that Matty Longstaff was fouled in the build-up fell on deaf ears.

Pogba received a warm reception when brought on at the start of the second half in place of Scott McTominay, who was booked after just 24 seconds and also came off worse in early challenges with the Longstaff brothers.

The substitute curled wide shortly after his introduction and Martial ended the contest six minutes after the restart, having read a foolish, underhit Sean Longstaff backpass and continued to lift the ball over Dubravka.

Pogba was denied and Martial hit the foot of the right-hand post as the home side looked to add further gloss, although Solskjaer took off the latter and Rashford with Saturday’s trip to Burnley in mind.

Harry Maguire was denied by a fine save and Pogba was unable to direct home as Man United looked most likely to score, but the match slowed down with the result assured.