Fulham kicked off at Craven Cottage seven points ahead of United, but on the basis of the first-half action, there was very little to separate these two sides.
Having his best goalscoring season to date, Alex Iwobi fired two low shots towards goal in the opening 20 minutes, each of which were dealt with rather comfortably by Andre Onana.
There were some neat passages of play during the first period, yet clear-cut chances were proving hard to come by, with neither side able to manufacture many openings of note.
The home fans may have been the more content heading into the break, having witnessed arguably the best opportunity of the half when Antonee Robinson looked to add to his nine PL assists, picking out Raul Jimenez, who blazed over from a tight angle.
The HT interval did little to energise the contest, with goalmouth action remaining at a premium as Bruno Fernandes sent a low free-kick into the side netting.
Remarkably, with over 20 minutes played in the second half, neither side had so much as a touch in the opposition area, highlighting the lack of attacking endeavour on display.
United had conceded first in eight of their last nine league games, but a wild effort from substitute Adama Traoré suggested the encounter was heading towards a goalless draw.
However, out of nowhere, the visitors grabbed the lead with 78 minutes on the clock thanks to Lisandro Martinez, who was alert to intercept a poor clearance before sending a heavily deflected shot from range in off the underside of the crossbar via Bernd Leno’s fingertips.
To that point, that was the Red Devils’ only attempt on target, but the travelling fans weren’t interested as they sang Ruben Amorim’s name.
A largely uneventful match almost had a moment of drama at the death as substitute Toby Collyer made himself a hero, clearing Joachim Andersen’s header off the line, shortly before Rodrigo Muniz wasted two presentable opportunities to test Onana.
A stoppage-time disallowed goal from Amad Diallo ultimately proved immaterial as United saw out a fourth win in five games across all competitions.
The victory somewhat lifts the mood and takes Amorim’s side to 12th in the PL standings, four points off Fulham, who remain inside the top half in 10th place.