Sunderland's Premier League status has been left hanging by a thread after their latest defeat.
Should Swansea City beat Middlesbrough tomorrow the Black Cats will find themselves ten points adrift if safety.
In truth that result may well be immaterial, for this was another game in which Sunderland fired a blank.
They have not scored since the 4-0 win over Crystal Palace and did not come close enough here either, even if Heurelho Gomes did make some fine saves.
Miguel Britos' back post header was the difference in the end, and it would have been more if Jordan Pickford had not shone again.
They improved in the closing stages but for the most part Watford were the quicker, more powerful outfit.
Didier Ndong was again left on the bench in a selection that did little to improve Sunderland's lack of pace and direct drive.
His bright cameo on the right flank will leave many baffled as to why he did not start the game. The return of Lee Cattermole and Victor Anichebe loosk like it will be too little, too late.
Watford's back three had a makeshift look about it to begin with, the influential Sebastian Prodl clearly missed. There were encouraging signs of Fabio Borini and Adnan Januzaj finding space inside the wing-backs, even if there wasn't a glut of chances for the visitors.
The pace and power at the other end for the hosts was abundantly clear from the off, Billy Jones doing well to head behind as M'Baye Niang attacked a cross at the back post.
Niang was a peripheral but occasionally electric presence down the left, at one stage powering clear of three Sunderland defenders. The Black Cats looked vulnerable to the counter throughout.
Sunderland did threaten, Jack Rodwell's effort deflected onto the roof of the net, Heurelho Gomes having to do well to turn Adnan Januzaj's shot wide.
Yet for the most part it was Watford creating the bulk of the efforts, and Jordan Pickford was the primary reason the visitors went into the interval level.
On 11 minutes he made a superb double save, pushing Niang's effort clear before pushing Abdoulaye Doucoure's effort wide with a firm right palm.
Stefano Okaka headed over a fine cross from Etienne Capoue, who was a dominant midfield presence, before shooting just wide from range ten minutes before the break.
The closest the Black Cats came was 42 minutes in, moments after Younes Kaboul went off with a hamstring injury. Januzaj's cross was deflected wickedly and Gomes was beaten, the ball spinning just wide. The corner was cut out, Watford racing clear at breakneck speed. Sunderland couldn't get close to the Hornets runners and Pickford had to do superbly again to stop Niang's drive.
The opening exchanges were notable mostly for an injury to Jermain Defoe, though the 34-year-old did recover after taking a blow in a challenge near the half way line.
Watford were the better side, Jose Holebas and substitute Isaac Success going close.
The deadlock was broken on the hour mark. A Hornets corner was met by a thumping header, Borini turning it into the bar. From the rebound the ball was headed back to the far post, where Miguel Britos towered above Borini and headed home.
That was the signal for David Moyes to bring on Didier Ndong, who took up an unfamiliar right-wing berth. He immediately brought some greater energy and when he cut back from the byline, Januzaj ought to have scored.
His effort was straight at Gomes, however, and it would have been 2-0 had Jordan Pickford not saved well from Isaac Success, who had raced through on goal after Lamine Kone was dispossessed.
Khazri replaced Januzaj, going into the book just moments later after remonstrating with the linesman. He did tee up Borini, whose long-range effort was turned wide by Gomes.