Wahbi Khazri gave Sunderland an early lead, before a David De Gea own goal with eight minutes remaining put the hosts back in front. Anthony Martial had equalised for United just before the interval, but the visitors were poor throughout and could have lost by a greater margin.
The Red Devils remain in fifth place in the Premier League table after this loss, six points behind local rivals Manchester City, who occupy fourth spot, having played one game more. Sunderland are now in 18th, one point back on rivals Newcastle United.
Much of the talk pre-match was about United closing the gap on their competitors for a top-four spot, but the hosts desperately need points to pull clear of a relegation scrap. And they began the game exactly like a side who were fighting for their lives.
Indeed, Sam Allardyce’s players put their opponents under pressure from the first whistle and within the first three minutes, they were in front. Granted, it came in fortuitous circumstances, as Khazri’s free-kick from wide on the left somehow found its way through a succession of bodies and past David De Gea.
Khazri, a January signing from Bordeaux, has been something of a revelation since signing for the Black Cats too, per OptaJoe:
2 - Wahbi Khazri has had a hand in two goals in his first two PL starts for Sunderland (one goal, one assist). Impact.— OptaJoe (@OptaJoe) February 13, 2016
The hosts didn’t let up after this early strike. Their direct playing style was causing the Red Devils a lot of problems, with Jermain Defoe missing a fine chance to make if 2-0 in the 10th minute. Meanwhile, at the other end, aside from a few flashes from Wayne Rooney, United were looking pretty toothless.
Bleacher Report’s Rob Blanchette was far from impressed with the manner in which the visitors began the game:
Sunderland making us look ordinary at times. Probably because we are. #MUFC— Rob B. (@_Rob_B) February 13, 2016
However, the Red Devils slowly started to get a foothold, and in Martial they possess a player capable of altering the course of a contest.
His strike was indicative of his exceptional composure in front of goal. The 20-year-old was fastest to react in the 39th minute as Juan Mata’s shot was parried by Vito Mannone, lifting the ball over the ‘keeper with the skill of a veteran striker.
Gary Lineker was impressed with what he had seen from the United No. 9, whose goal saw his side go in level 1-1 at the break:
Martial has it all. He's going to be one hell of a player.— Gary Lineker (@GaryLineker) February 13, 2016
As they'd done at the beginning off the match, Sunderland flew out of the traps in the early stages of the second period, with United again unable to cope.
First they had a penalty appeal turned down, as John O'Shea's header struck Rooney on the arm. Then Defoe had an effort cleared off the line by Daley Blind, before De Gea produced a superb save to deny Dame N'Doye, who had surged into the penalty area after positive play on the right flank.
It was a trademark stop with his feet from the Spain international; as noted by Men In Blazers, they're moments he seems to produce in every game:
David De Gea makes weekly acts of heroism seem both casual and routine— Men in Blazers (@MenInBlazers) February 13, 2016
There were glimpses of attacking flair from the Red Devils, but they were finding it tough to put together their patterns in the final third.
Indeed, as the clock ticked past the 70-minute mark, Sunderland continued to look the most threatening of the two sides, with De Gea again called into action. This time the goalkeeper was at this best to claw away a fine strike from Lamine Kone that was destined for the top corner.
The defender wasn't to be denied, though, as he was key in giving the Black Cats a deserved lead with the clock ticking down. Khazri was again involved, as his corner found Kone, who thundered a header at goal; De Gea did get a hand to the effort but was unable to keep it out.
As noted by Squawka Football, defensive issues have gripped this United team in recent weeks and they looked set to cost the Red Devils again:
Man United have now conceded 2+ goals in four of their last six Premier League away games. pic.twitter.com/ur1e7dVEwZ— Squawka Football (@Squawka) February 13, 2016
It was a blow United were unable to respond to and led to a loss that will heap further pressure on manager Louis van Gaal.
With league leaders Leicester City travelling to Arsenal and Manchester City hosting Tottenham Hotspur on Sunday, this was a brilliant chance for the Red Devils to put some pressure on the sides above them. So Van Gaal will be hugely disappointed to see his team drop points against a side battling to stay afloat in the division.
Sunderland deserve credit for the manner in which they approached this game, though. They put United under pressure throughout and the home crowd responded to roar the players on to a famous win. In Khazri and Kone, Allardyce seems to have picked up a couple of gems in the transfer window too.
Afterwards Van Gaal admitted his side were unable to cope with the tenacity of Sunderland, per BBC Sport's Simon Stone:
LVG: "You have to win this kind of game. We can only blame ourselves. We could not cope with Sunderland's aggression."— Simon Stone (@sistoney67) February 13, 2016
LVG: "Top four will be very difficult now. We have given five points away."— Simon Stone (@sistoney67) February 13, 2016
LVG: "I have told the players the top four will be very difficult. You cannot close your eyes to that."— Simon Stone (@sistoney67) February 13, 2016
Rooney also conceded a top-four finish is now very unlikely for the Red Devils, per Stone:
Rooney: "It will be difficult to qualify for the Champions League through the top four now."— Simon Stone (@sistoney67) February 13, 2016