A Jay Rodriguez rocket piled further pressure on Ole Gunnar Solskjaer as Burnley stormed to a 2-0 victory over United at Old Trafford.
The Red Devils had a gilt edged opportunity to close the gap to three points on fourth-placed Chelsea, who slipped up to draw with 10-man Arsenal on Tuesday.
But United failed to take their chances despite dominating most of the first half against the Clarets, before the away side opened the scoring against the run of play.
Chris Wood broke the deadlock on the stroke of half time after latching onto a headed-down ball fired into the box from a long-range free-kick.
Wood turned provider for the second when he fed Rodriguez after the restart
The Burnley graduate channelling his namesake to James Rodriguez thunder a shot in-off the crossbar and beyond the reach of David de Gea to wrap up the points.