Second half goals from Romelu Lukaku and Alexis Sanchez, his first for the Red Devils, were enough to condemn the Terriers to a fifth straight league defeat.
Thanks to results elsewhere, this latest reverse was enough to dump David Wagner’s men into the bottom three.
Town battled hard but simply had no answer as the home side stepped up their efforts after the break.
The breakthrough came ten minutes into the second half, Town opened up down their right flank as Juan Mata was played clear.
His cross was inch-perfect for Romelu Lukaku, whose first time volley gave Jonas Lossl no chance in the visitors’ goal.
United doubled their lead midway through the second half, as Michael Hefele, on for Christopher Schindler, tripped Sanchez inside the penalty area and referee Stuart Attwell pointed to the spot.
Jonas Lossl saved the Chile striker’s spotkick but was unable to do anything about him firing in the rebound.
Town, who offered little of note in attack even after falling behind, had enjoyed a fortunate escape in the first half when Terence Kongolo clattered into Scott McTominay inside the penalty area only for Stuart Attwell to rule no foul had taken place.
Jonas Lossl also had to get down smartly to deny both Jesse lingard and Alexis Sanchez but, otherwise, the visitors had looked comfortable in those opening 45 minutes.
Then, though, Lukaku broke the deadlock and there was simply no way back for the Terriers as they slipped into the relegation zone for the first time this season.
David Wagner said:
“We were aware that this is a difficult task in front of us, we wanted to be solid defensively and find a good formation where we frustrated them, and I think it worked. We were not able to create our moments in the offence because United were concentrated and focused at avoiding our transitions.
“Unfortunately, we made a mistake and conceded the first one, then we made an individual mistake for the second one. It’s frustrating because the players worked so hard but on the other side we have to be honest. These have been difficult fixtures in the last four days with Liverpool and Manchester United.
“What I have seen today, the commitment and working effort, gives me hope for what’s in front of us. We now have fixtures at home where we have to get this atmosphere and this vibe in the dressing room, in the stands and in the Town that’s all about surviving in the Premier League.
“We now have these fixtures in front of us where we have the chance to pick up points and we will prepare for this.”
Now comes the real test for Huddersfield Town.
After back-to-back games against Liverpool and Manchester United, the Terriers’ next league assignment is the February 11 home clash with Bournemouth.
It is the first of four consecutive home games that are eminently winnable, even for a side so badly out of form as Huddersfield.
Watford, Crystal Palace and Swansea City are the visitors during a two-month period that also includes trips to Newcastle, West Brom and Brighton, plus Wembley to tackle Tottenham. This run of games will decide Town’s fate.