Dave Jones felt the pressure on his future build immeasurably on a night when Sheffield Wednesday capitulated.
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.
Wednesday seized their opportunity when Watford conspired to gift possession to Antonio and the former Reading winger gleefully accepted the invitation, slotting past the onrushing Manuel Almunia with calm assurance.
But Wednesday 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.
On the half-hour mark 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.
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.
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.
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.