A Gylfi Sigurdsson free-kick dealt a blow to Manchester United's hopes of a top four finish whilst boosting his team Swansea's chances of escaping the drop in an entertaining 1-1 Premier League draw on Sunday.
Wayne Rooney had scored his first home league goal of the season, from a harsh penalty decision, in time added on of the first-half.
However, he blotted his copybook when he conceded a free-kick nearly 25 yards from goal in the 78th minute.
Free-kick specialist Sigurdsson duly delivered with a superb curling effort into the top corner that left United keeper David de Gea rooted to the spot and denied Jose Mourinho a victory that would have lifted United into third place, temporarily at least.
Instead they trail fourth-placed Manchester City on goal difference and could fall three points behind them if City beat struggling Middlesbrough later on Sunday.
Swansea, who have righted the ship a little in taking four points from their last two games after a return of just a single point in the previous six, trail fourth from bottom Hull by two points with three matches remaining.
Rooney struck in first-half injury-time after a contentious penalty award by referee Neil Swarbrick who judged keeper Lukasz Fabianski had brought down Marcus Rashford when diving at his feet.
Replays suggested Swansea had been hard done -- Rashford making the most out of minimal contact -- but Rooney made no mistake with a clinical conversion from the resulting penalty.
It was a cruel end to a strong showing by Swansea and a slow start from Mourinho's side was exacerbated by an injury after just seven minutes to England left-back Luke Shaw who appeared to damage his ankle off the ball.
The tactical reshuffle that followed hardly helped United settle as they struggled to cope with an impressive and committed opening from the relegation-troubled visitors.
Indeed, Paul Clement's side should have gone in at the half-time interval in front.
On 12 minutes, Ayew's shot was blocked by Eric Bailly who blasted his clearance directly at Sigurdsson and watched, relieved, as the ricochet flew harmlessly behind.
Then Fernando Llorente beat Bailly far too easily and was only denied by a flying stop from de Gea.
United had given Fabianski something to think about, starting in the 16th minute when Anthony Martial picked out the well-timed run of Jesse Lingard with a pass which the youngster volleyed too close to the Swansea keeper.
Martial was looking increasingly dangerous as he cut in from the left and a grateful Fabianski smothered his shot at the second attempt as Lingard was poised to net the rebound.
And before United would take the lead, there was a reminder that Swansea posed a real threat as Tom Carroll found Ayew whose shot was blocked by the outstretched leg of de Gea with the loose ball flying within inches of two Swansea attackers.
Rooney should have handed United a much-needed two-goal cushion early in the second half as he exchanged passes with Ander Herrera but succeeded only in striking his effort directly into the back of Martial from eight yards.
Mourinho's mounting injury list grew when the impressive Bailly limped out of the game with what looked like a hamstring problem on the hour mark.
As Clement chased the game, Swansea also ran into injury problems with substitute Jefferson Montero managing to survive just six minutes before being stretchered off.
Even after their equaliser, Swansea still pushed for a winner, however, and Llorente should have done better than mis-kick close to goal from another threatening Sigurdsson set-piece.