The Magpies got off to an encouraging start at Old Trafford and took the lead through Dwight Gayle, who capped off a fine passage of play to net his first goal of the season.
They kept the Red Devils at bay for much of the first half, only for Anthony Martial’s leveller to take the wind out of their sails.
Chris Smalling completed a quickfire turnaround on the stroke of half time, before Paul Pogba and Romelu Lukaku added a touch of gloss to the scoreline after the break.
The Magpies had been forced to withstand a scare early on. Antonio Valencia played a one-two with Marcus Rashford wide on the right before sending in a low cross for Lukaku, who cleared the crossbar under pressure from Florian Lejeune.
Newcastle started to find their feet, though. Successive corners came and went two minutes later, the second of which was nodded over the crossbar by Ciaran Clark.
Then, after a flowing move on the right, the visitors took the lead. DeAndre Yedlin powered down the flank, exchanged passes with Gayle, and then looked to set the frontman up with a cutback. Victor Lindelöf appeared to have it covered, but the Swede slipped, allowing Gayle the chance to find the net via the far post.
It could have got even better for the Magpies five minutes later. Jonjo Shelvey split the Red Devils’ backline with a fine threaded pass, and Jacob Murphy’s low-struck effort rolled just the wrong side of the upright.
As the first half wore on, though, José Mourinho’s side began to assert themselves in the final third. Lindelöf almost atoned for his part in Newcastle’s goal by delivering a floated ball for Lukaku, who headed high and wide.
But, with their next meaningful attack, the hosts restored parity. Pogba – returning to action after a two-month absence – engineered a yard of space for himself just outside the area, and put the ball on a plate for French compatriot Martial.
And, just as Benítez’s side looked set to head into the break on level terms, the Red Devils struck again. Ashley Young’s left-footed delivery swung over the top of the Magpies’ defence, and Smalling – perched at the back post – guided the ball beyond Rob Elliot.
Even then, though, the hosts had ‘keeper David de Gea to thank for their half-time advantage, the Spaniard getting down to parry Isaac Hayden’s effort after the midfielder found a pocket of room 12 yards out.
Ten minutes after the break, though, Pogba all but put the outcome beyond doubt, applying the finishing touch to a neat counter-attacking move. Lukaku gathered the ball on the right and crossed for Rashford at the back post, who nodded down for the midfielder to tap in.
The Magpies took their time to recover after that, but with 25 minutes remaining, Murphy brought a decent save out of de Gea after taking aim from range.
But, within the blink of an eye, the home side duly added to their advantage. Lukaku – without a Premier League goal since September – gathered Juan Mata’s pass before keeping his composure and rifling the ball past Elliot.
Shelvey almost pulled one back for Newcastle with ten minutes to play, a flat-footed de Gea grateful to see the ball whistle past the far post.
The last word, however, nearly belonged to another long-term absentee, as frontman Zlatan Ibrahimović saw an acrobatic effort pushed wide by Elliot in the dying embers of the game.
