Frantic finish at Vicarage Road as United move to Premier League summit with late winner
Troy Deeney went from hero to villain in the space of five minutes as the Watford striker scored a late penalty and then an own goal to give Manchester United a 2-1 victory at Vicarage Road.
Watford looked to have snatched a point when Deeney's 87th-minute spot-kick cancelled out Memphis Depay's early opener, but the Hornets captain bundled in Bastian Schweinsteiger's cross moments later to give Louis van Gaal's side a valuable three points.
The win means United are now unbeaten in eight in all competitions.
Deeney had invited six former inmates from his three-month spell in prison in 2012 to watch the contest but despite his third goal in four matches, he failed to get Watford out of jail as they sank to their fifth defeat of the season.
Vicarage Road was the first Premier League ground of the weekend to play La Marseillaise before kick-off, in tribute to victims of the Paris terrorist attacks eight days ago.
United fans added their own personal touch, chanting 'Ooh ah Cantona' with the music, before the anthem's end was greeted with a warm round of applause from both sets of supporters.
United's primary failing this season has been in the final third and their attacking prospects at Vicarage Road were not helped by a shortage of strikers, with Wayne Rooney ill, James Wilson lacking fitness and Anthony Martial out with a foot injury.
It meant a first league start for Depay since United's 3-0 defeat to Arsenal on October 4 while youngsters Marcus Rashford and Sean Goss were named on the bench.
Depay's United career has been one of fits and starts since his £31million move in the summer but Van Gaal may have stumbled upon a temporary solution to his side's attacking woes, with the striker offering the kind of movement and speed in behind that has been so lacking in recent weeks.
It took only 11 minutes for the 21-year-old to break the deadlock as Ander Herrera whipped in a superb cross from the right, and Depay applied a sweet side-foot volley into the top corner.
The goal knocked the stuffing out of Watford but the hosts could have equalised when Etienne Capoue nicked the ball off Ashley Young near the halfway line and, with United caught upfield, he set Odion Ighalo free but the forward took too long before blazing over.
United remained largely in control, however, and Morgan Schneiderlin twice went close to doubling their advantage, first volleying over from an acute angle and then sliding in for a tap-in before Deeney's crucial touch diverted the ball to safety.
The last notable action of the first period saw Heurelho Gomes skew his kick straight to the feet of Depay but the forward delayed his pass to an offside Juan Mata, with Watford going into the break relieved to be only one down.
The Hornets were under the cosh again soon after the restart as the lively Jesse Lingard saw his shot palmed wide by Gomes and it was not until the hour mark that Quique Sanchez Flores' side began to enjoy their first spell of pressure.
Deeney's thundering half-volley had to be pushed away by David de Gea, then Ighalo's close-range finish was blocked by Schneiderlin, before United's keeper was again called into action to deny Almen Abdi's dipping shot.
Suddenly, United's previous dominance had diminished and in the 75th minute Van Gaal leapt out of his seat to lambast Chris Smalling, after the otherwise impressive defender had allowed Deeney another drive at De Gea.
Lingard should have put the result beyond doubt when he latched on to Daley Blind's lofted ball down the middle, but his attempted lob dropped harmlessly into the hands of Gomes.
It almost proved costly as three minutes from time Marcos Rojo swiped through the back of Ighalo and referee Bobby Madley pointed to the spot.
Deeney slammed the penalty down the middle to the ecstasy of the home supporters, but they had barely retaken their seats when, a minute into injury time, he then bundled in Schweinsteiger's pull-back to gift the Red Devils the narrowest of victories.