Swansea recovered from a goal down to come from behind and seal a hat-trick of 2-1 wins over Louis van Gaal's side in the manager's 50th match in charge.
Juan Mata had put United ahead early in the second half but- after Garry Monk's tactical alterations and two goals in quick succession- the Swans beat us again and leave LVG still searching for a win against the South Wales side.
Memphis Depay went close with a dangerous free-kick that was well saved by Lukasz Fabianski and Mata nearly scored from Ander Herrera's cut back in a bright start from the visitors.
Swansea began to exert their attacking threat on the match though and, after Gylfi Sigurdsson flashed an effort across goal, Sergio Romero saved well from Jonjo Shelvey before the impressive Bafetimbi Gomis rattled the woodwork from close range.
Monk's side had arguably edged a thrilling first half but, three minutes into the second half, United were ahead.
The Reds best player, Luke Shaw, fizzed in a cross that evaded everyone except Juan Mata at the back stick and the Spaniard stuck out a leg to stab in.
Seven minutes later, the game changed on a slight tactical tweak by the hosts- who introduced Ki Sung-Yeung (who scored twice against us last season), reverted to a midfield diamond and pushed the superb, relentless Andre Ayew further forward.
On the face of it, this seemed a surprising switch but Monk's decision was vindicated just four minutes later when Ashley Williams picked out Sigurdsson who crossed for Ayew to head in.
Five minutes later, Swansea struck again and the build up was simply exquisite.
Shelvey found Sigurdsson who flicked on to Ayew whose glorious defence-splitting ball picked out Gomis who ran through and side-footed home what turned out to be the winner.
Marouane Fellaini was thrown on as an emergency striker- typifying the Reds dearth of attacking options- but the Reds were unable to respond as Swansea kept hold of their recent grip over van Gaal's side on a disappointing afternoon.
United Faithful man of the Match: Juan Mata
Overall team performance: 6/10