Dave Jones felt the pressure on his future build immeasurably on a night when Sheffield Wednesday surrendered an early lead, missed a penalty and then capitulated.
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The Owls boss must have been a relieved man when Michail Antonio put his side ahead as early as the third minute, but it did not last.
Fernando Forestieri levelled 15 minutes later before Chris Lines saw his first-half spot-kick saved.
Alexandre Geijo's strike midway through the second half put Watford deservedly ahead and substitute Troy Deeney then scored with his first touch.
The visitors saved the best until last, Mark Yeates curling home a beautiful long-range effort to complete an unbeaten November for the visitors in style.
The opening quarter of the match was characterised by poor defensive errors, and after Anthony Gardner atoned for his own misplaced header with a fine sliding challenge on the goal-bound Forestieri, Wednesday seized their opportunity.
The Hornets conspired to gift possession to Antonio and the former Reading winger gleefully accepted the invitation, slotting past the onrushing Manuel Almunia with calm assurance for his fifth of the campaign.
It provided only momentary relief for the hosts, aiming to improve on a run of just two wins in 16 league and cup matches.
They switched off at a throw-in 18 minutes in, allowing Daniel Pudil to find Forestieri, who in turn located the bottom corner from 15 yards for his third of the season.
An air of unease fell around Hillsborough, which only grew when hapless defending from Gardner and Miguel Llera presented Forestieri with the opportunity to shoot - he did, but found the outside netting at Chris Kirkland's near post.
On the half-hour mark all that frustration should have been blown away when Jay Bothroyd was sent tumbling in the box by Pudil, who was fortunate to escape with a yellow card.
With QPR loanee Bothroyd off receiving treatment, Lines, making his first start of the season, stepped up but his shot was weak and Almunia gathered with ease down to his right.
With the scores level at half-time, Gardner made way for Martin Taylor but the Owls' defensive frailties were exposed within two minutes of the restart.
Marco Cassetti scampered down the right, dug out a cross for Geijo and his downward header was scrambled around the post by Kirkland.
Referee Tony Bates withdrew himself from the action after an hour, injury apparently curtailing his involvement, with fourth official Tony Harrington on to replace him.
Llera was next to lose his concentration and subsequently the ball, feebly allowing an unthreatening through-ball to flick off his knees and into the path of Forestieri, who forced a fine save from Kirkland.
There was an air of inevitability about what happened next. Wednesday's defence switched off at a free-kick and Geijo headed in his first goal for the club from six yards after 67 minutes.
Jones brought on Jermaine Johnson in the immediate aftermath of the goal and was greeted by a chorus of boos from the home crowd.
The mood worsened when Deeney, brought on only moments earlier, pounced on a loose ball in the box to rifle home with his first touch.
Yeates' stunning 25-yarder seven minutes from time sparked a mass exodus from three sides of the ground and a deflated Jones could only watch on as Bothroyd somehow blasted well over the bar with the last kick of the game.
Wednesday remain in the relegation zone having now lost five on the bounce, but upwardly mobile Watford have taken 14 points from six games this month and the play-offs are within reach of Gianfranco Zola's men.