Manchester United 1 - 0 Everton
Phil Jagielka came closest to salvaging a point but saw a header cannon off the bar and David de Gea deny him later with a point-blank reaction save
Everton slumped to a fourth defeat in their last five League games as Anthony Martial's second-half strike was enough to overcome Roberto Martinez's toothless side.
The French striker stole in behind a napping Seamus Coleman and converted Fosu-Mensah's low cross from the right off Joel Robles in the 54th minute in what was a rare moment of incision from either side on an afternoon short on goalmouth action.
Phil Jagielka thumped a header off the crossbar and was later denied by a reaction save from David de Gea from another set-piece but that was as close as the Blues came to rescuing anything from the match.
Martinez's response to the dire home defeat to Arsenal before the international break was to drop Ramiro Funes Mori back to the substitutes' bench and reinstate John Stones to the back line. Gerard Deulofeu was also recalled from his recent exile on the bench, deployed mostly on the right flank, although he and Aaron Lennon traded places to decent effect in the first half.
The Spaniard was lively in the early going, skinning Marcos Rojo on two or three occasions down the flank and later skipping dangerously into the box before over-running the ball at the last moment.
Looking to largely contain their hosts in the first half, Everton struggled to create anything meaningful in front of the opposition goal and it was Louis van Gaal's men who carried the greater threat.
Martial flashed a 17th-minute shot inches wide of Joel Robles' post as United looked to exploit the space in front of Everton's back four while Stones's last-ditch tackle eight minutes from the break was required to stop the teenager from bursting through on goal.
With neither side looking all that convincing in the first half, the match felt like it was there for whichever side could grasp it by the scruff of the neck and it looked, for the first few minutes after the interval, that that might be Everton.
Leighton Baines's perceptive pass into the heart of United's area in the 49th minute found Romelu Lukaku superbly in front of goal but while the Belgian rolled Daley Blind, his shot on the turn deflected off the Dutchman's leg and behind for a corner.
Deulofeu was then fouled by Blind and Tom Cleverley's fired a shot into Smalling's body but it was a spell of Blues pressure that was broken a couple of minutes later by Martial's goal.
After Jagielka hit the woodwork, Jessie Lingard came close to doubling the Red Devils' lead when he slid in trying to connect with Juan Mata's low cross while Martinez's men struggled for fluidity and incisiveness.
The Catalan withdrew Deulofeu in favour of Kevin Mirallas but Lukaku continued to toil as the lone striker and it wasn't until an 83rd-minute corner that Everton threatened again when Jagielka's close-range shot was parried away by De Gea.
Oumar Niasse was thrown on in place of Ross Barkley on as a fruitless last throw of the dice but apart from a low Coleman centre that just eluded Lukaku, the Blues didn't really look likely to salvage anything from the match.
The defeat, just the second away defeat in the League all season, leaves Everton adrift in 12th place, albeit with two games in hand on some of the clubs above them, and one game closer to finishing in the bottom half for a second successive season.
Full coverage: ToffeeWeb match page