Wayne Rooney returned to form with a brace, while Jesse Lingard also netted for the Red Devils. Goals from Georginio Wijnaldum and Aleksandar Mitrovic kept the home side in contention before Dummett made his mark.
United actually went two up only to see the home side battle back to equalise. Rooney put the Red Devils ahead again before Dummett had the last word.
Magpies boss Steve McClaren partnered Ayoze Perez with Mitrovic up top, while gifted attacking midfielder Wijnaldum provided support. The club tweeted the starting XI:
United chief Louis van Gaal tasked young winger Lingard with supporting Rooney and Anthony Martial, per the club's official Twitter feed:
The visitors sat deep early on, keeping a fairly rigid shape. Ander Herrera wasn't pushing forward to get on the ball and pull the strings.
That gave the Magpies the initiative. With Moussa Sissoko and Wijnaldum making runs, Newcaslte were able to commit numbers forward.
Controversy occurred when the Reds made a rare foray forward. Daley Blind's out-swinging corner was judged to have been handled by Chancel Mbemba to take the ball off the head of Marouane Fellaini.
Mike Dean made the call and Rooney converted from the spot to give the Red Devils the lead. The goal marked a rarity for Rooney in England's top flight in recent years, according to Squawka Football:
Wayne Rooney has scored in consecutive Premier League matches for the first time since November 2014. pic.twitter.com/OXGhGclBKM— Squawka Football (@Squawka) January 12, 2016
It also maintained Rooney's historic run of tormenting Newcastle, per OptaJoe:
13 - Wayne Rooney has scored his 13th Premier League goal against Newcastle; his joint-favourite opponent along with Aston Villa. Lucky.— OptaJoe (@OptaJoe) January 12, 2016
Rooney should have doubled the lead later in the half. He combined well with Lingard but fired past the post from a one-on-one situation. At the other end, Wijnaldum was denied by David De Gea after being teed up by Perez.
Fellaini was living a charmed life. He made four fouls before finally seeing a yellow card and narrowly avoided a second booking.
Not long after, Newcastle right-back Daryl Janmaat was bundled over in the box by Lingard, but Dean was unmoved. The home side was soon left to rue that call when United went two up.
When it came, the goal was wonderfully worked. Blind intercepted a pass on the edge of his box. Herrera then released Rooney in the inside left channel. The striker smartly delayed and fed a reverse ball to the buccaneering Lingard. He promptly slotted home via a sweet side-foot finish.
Rob Dawson of the Manchester Evening News offered semi-mock praise for what he saw as rare attacking impetus from Van Gaal's men:
That's a fantastic goal. Amazing what can happen when you attack with pace and pass the ball forward.— Rob Dawson (@RobDawsonMEN) January 12, 2016
In response, Fabricio Coloccini broke from the back to try to revive Newcastle. The Argentinian centre-back's rasping shot went narrowly over.
Coloccini was influential again when Newcastle actually did score. He chipped in for Mitrovic to nod down in the box. Wijnaldum latched on to it and finished in style.
He's made St James' Park a happy hunting ground since signing last summer, per WhoScored.com:
Georginio Wijnaldum: Has scored each of his 8 Premier League goals at St. James’ Park #nufc— WhoScored.com (@WhoScored) January 12, 2016
The goal also ended a prolonged drought for the Magpies, according to Lee Ryder of the Newcastle Chronicle:
First goal in 454 minutes of football for #nufc— Lee Ryder (@lee_ryder) January 12, 2016
Newcastle were in the mood as the second half began. Sissoko tied United defenders in knots before shooting right at De Gea.
The visitors made their own chance when Martial broke into the box and fed Herrera. The Basque playmaker rolled a blind backheel Lingard's way, but the winger blasted over. It was a terrible waste of an otherwise fine move.
Van Gaal was certainly left fuming, something Dawson poked fun at:
Last time Van Gaal reacted like that to a miss he sent Javier Hernandez to Germany.— Rob Dawson (@RobDawsonMEN) January 12, 2016
Lingard was soon hooked in favour of Memphis Depay.
Newcastle should have made Lingard's miss really count and drawn level through Jack Colback. The midfielder was sent clear in the box by an excellent prodded pass from Wijnaldum. But instead of shooting, Colback inexplicably delayed and tried to draw a penalty from Fellaini.
The Magpies didn't have to wait long for a penalty, though. Chris Smalling mauled Mitrovic to the floor, prompting Dean to point to the spot. Mitrovic then rolled in to level the score.
Wijnaldum had a goal chalked off for offside soon after the restart. The men from Manchester were certainly reeling.
In particular, Newcastle were bossing proceedings down the right, as Stuart Mathieson of the Manchester Evening News noted:
Blind and Darmian are getting taken apart down the left. Sissoko loving it #MUFC— Stuart Mathieson (@StuMathiesonMEN) January 12, 2016
But United rode their luck and went back in front when Depay ran at the Newcastle defence. His shot deflected and fell nicely for Rooney, who struck it true for an emphatic second goal.
The strike confirmed Rooney is back to his very best:
Wayne Rooney has now scored 4 goals in his last 3 appearances for Man United. Loving it out there tonight. pic.twitter.com/AC02aS2JFq— Squawka Football (@Squawka) January 12, 2016
Fellaini should have wrapped up the points but saw his point-blank header saved by Rob Elliot. The stop would prove vital.
Dummett would be the man to break United hearts when he thundered home a Newcastle equaliser in the last minute. His deflection had set up Rooney's goal, but the full-back ultimately had the last laugh.
Van Gaal felt his team was unlucky, particularly in the manner in which they conceded the equaliser. But he also bemoaned his players inability to finish the game off:
By contrast, McClaren felt his players had answered some of the criticism about their collective character, following a poor start to the season, per BT Sport Football:
McClaren's men still haven't escaped the bottom three but will certainly welcome this point. As for United, they are in the unfamiliar confines of sixth place ahead of facing arch rivals Liverpool, who are just four points and two places behind.
Under-fire Van Gaal was denied what would have been a very welcome reprieve. For a rare time, his team delivered some excellent and attractive football going forward, but they creaked fatally at the back.
As for Newcastle, McClaren's men just can't find the luck they need to turn committed performances into wins.