They were three enforced substitutions in the space of just six minutes, but that was the lucky break Newcastle United needed as they won for the first time this season to emerge from the Premier League bottom three.
The matchwinner was Ayoze Perez, flashing home a header from Ki Sung-Yeung’s free-kick midway through the second half.
That pair had earlier replaced the injured Yoshinori Muto and Jonjo Shelvey, while the third change, defender Fabian Schar, was just as influential after he replaced captain Jamaal Lascelles.
Ayoze Perez’s smart header proved enough for Newcastle to earn their first victory of the season against Watford
The striker’s first goal of the season was the matchwinner on 65 minutes… but the Hornets had dominated the first hour
Gerard Deulofeu was guilty of missing two good chances for Javi Gracia’s side and Roberto Pereyra hit the bar on 50 minutes
Stefano Okaka (centre) had the game’s final chance, firing the ball well over the bar in stoppage time from close range
Newcastle’s supporters had listened to manager Rafa Benitez and did not boo Lascelles after his comments this week about unpopular owner Mike Ashley being a ‘nice guy’.
They did, however, jeer the introduction of Perez and he responded after his sublime finish by putting fingers in both ears.
The home victory did not look at all likely after an abysmal first half.
Newcastle wore the look of a team bereft of confidence and waiting for something to happen, so ponderous and predictable they were when in possession.
Watford, meanwhile, had a pace and purpose about their play and it was a mystery to all inside the stadium how the first half expired with the score goalless.
A minute’s silence was observed to commemorate Remembrance Sunday and to remember those who died in Leicester
Gerard Deulofeu looked most likely to break the deadlock for Watford – he had three good chances in the first half
He saw his first effort go wide of the goal… before missing the target again when played through on Martin Dubravka’s goal
Striker Isaac Success was a thorn in Newcastle’s side all afternoon and he also scuffed an effort wide of the post
Hornets’ French midfielder Etienne Capoue was booked for fouling Newcastle striker Yoshinori Muto
Jonjo Shelvey bent the resulting free-kick over the bar for Newcastle, who struggled to create chances in the first-half
Muto then had to be taken off in stoppage time at the end of the first half, Perez came on to replace the striker
Defender Adrian Mariappa, up from the back for a corner, dragged wide from 10 yards after a goalmouth scramble which began with his shot being blocked on the line by Lascelles.
The panic of that episode spread to Newcastle’s general play, the sight of Kenedy rolling a simple five-yard pass behind team-mate Shelvey symptomatic of their nervousness.
They did have one or two moments of promise, but visiting goalkeeper Ben Foster was never going to be beaten by a pair of Mo Diame and Kenedy efforts, even if they did draw saves.
At the other end Gerard Deulofeu should have climaxed a swift break with a goal but stabbed wide from an Isaac Success pass.
And Success himself was unlucky when Martin Dubravka turned his low drill around the post just before half-time.
So superior had Watford been, the first half had the feel of a senior side taking on the under-23s.
Ben Foster was largely untroubled in the Watford goal prior to Perez’s header, which came against the run of play
The Spaniard was handed the freedom of Watford’s penalty area to direct his header beyond Foster and into the net
Perez put his hand in his ears during the celebrations after being booed when he was brought on to replace Muto
Andre Gray was sent on by Gracia to try and find an equaliser… but Kenedy did enough to put him off
Newcastle boss Benitez congratulates Perez at the final whistle after his header ended their 11-game wait for a win
The relief and joy on the Newcastle players’ faces was clear for all to see as they celebrated with each other
On the other hand Watford players could not believe they were leaving St James’ Park with nothing after the defeat
Newcastle owner Mike Ashley was again in attendance at St James’ Park and looked in good spirits after Perez’s strike
Not so after the break as Benitez’s trio of substitutes changed the game.
The goal arrived on 65 minutes as Perez silenced those who had grumbled when he entered the action for Muto in first-half injury-time.
But Schar was just as influential, driving the team forward from the back with an aggression and urgency which had been lacking in the opening 45 minutes.
A Newcastle second looked inevitable – it is not often that has been said this season – and Salomon Rondon shaved the post with a header from Kenedy’s looping centre.
But the Magpies needed Kenedy moments later to preserve their lead as he slid inside the six-yard box to steal from the toe of Andre Gray, the substitute poised in anticipation of a tap-in after yet more good work from Success.
Fellow sub Stefano Okaka then blazed over from eight yards in stoppage-time as Newcastle rode their luck.
For once, the breaks went with them, none more so than the three substitutions.