As the game petered out in soaking conditions, teenage substitute Ryan Andrews recklessly lunged into a challenge which saw him dismissed, taking the Hornets' night from bad to worse.
Here are the player ratings after a very one-sided affair.
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Sunderland
Anthony Patterson - 7
A relatively quiet evening for a man who grows in confidence with every game he plays. He wasn't called upon all too often, but when he was, his concentration was spot on when dealing with the slippery surface.
Niall Huggins - 9
First senior goals don't come much better than Huggins'. He split through the Watford defence like a knife through butter and capped off his weaving run with a belter into the top corner.
An accomplished performance in both aspects of his game, Huggins was full of energy and never stopped patrolling the right-hand side.
His nimble footwork and desire to win the ball back resulted in a tremendous display, and his goal just before half-time really put Sunderland in the drivers seat.
Daniel Ballard - 6
Ballard marshalled Vakoun Bayo out of the game commandingly when needed and aerially dominated in both boxes.
He squandered a great opportunity to double Sunderland's lead with a poor header, but other than that, he was fairly faultless.
Luke O'Nien - 8
With him being the constant in this ever-growing Sunderland side, O'Nien's progression has been nothing short of remarkable.
Ever since his release from Watford in 2015, he's been making his boyhood club rue their mistake with his adaptability, determination and leadership.
Another flawless display at centre-back from the club captain saw him really test the Watford players' temperaments, as well as shut out a handful of dangerous opportunities for the away side.
Trai Hume - 6
A steady performance which didn't include many memorable moments.
He consistently gave Jack Clarke the ball and made plenty of intelligent runs to support his winger which troubled the Watford defence.
Dan Neil - 7
Neil has made an excellent start to the campaign, and that continued with a composed and disciplined display against Watford.
He grabbed the assist for Huggins' goal, and successfully controlled the tempo of the game with his sensible decision-making and crisp passing.
Patrick Roberts - 7
After bouncing around six different clubs on loan from Manchester City in the past six years, Roberts finally looks settled in Wearside and is proving to be the player we all thought he could be when he burst onto the scene as a youngster.
His positional understanding was clear to see as he picked up threatening positions both in central areas, and out wide.
He supplied some excellent touches in the first-half, but lacked the clinical edge to turn his aesthetically pleasing play into clear-cut chances.
Jobe Bellingham - 8
He grew into the game after a slow start and some indecisive actions in the final third.
Just like his brother, Jude Bellingham, he is showing enormous signs of maturity in his game and that showed in the second-half when he understood at what time he could be direct, and what moment he should maintain possession.
His movement in and around the box comes naturally to him, and it was pivotal in providing the assist for Ba's goal which put The Black Cats out of sight.
Abdullah Ba - 7
The young Frenchman came in for Alex Pritchard and notched his second goal of the season with a simple finish.
He showed glimpses of promise with his pace, but similarly to the rest of his attacking teammates in the first-half, he struggled to make some nice play count for more.
Mason Burstow - 6
The Chelsea loanee got his fifth-consecutive start leading the line, and offered sufficient link-up play to allow his more creative teammates to thrive.
His enthusiasm to impress was evident, but perhaps not effective as he was rarely in the right place when the final ball was delivered into the box.
Jack Clarke - 8
Clarke has arguably been the Championships finest player this season, adding goals to his already elegant style.
He was the one that brought fluidity and danger to Sunderland's attacks as he was breezing past Watford defenders with ease.
The former Tottenham prospect caused havoc on the left-flank, resulting in Jeremy Ngakia's half-time substitution.
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Substitues
Adil Aouchiche (Roberts 71') -
He lacked conviction when rushing through on Bachmann's goal as he squandered a great chance to truly put the game out of sight.
He picked up where Roberts left off and played his part in keeping the ball and comfortably seeing out the game.
Nazariy Rusyn (Clarke 90+1') - N/A
Silva Semedo (Burstow 90+1') - N/A
Chris Rigg (Bellingham 90+6') - N/A
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Watford
Dan Bachmann - 6
Whilst the goals conceded couldn't really be prevented by the Austrian, he failed to instil confidence into his side with some stodgy passes out from the back.
He did make a crucial stop to prevent Sunderland scoring a third, but by that point the real contest was already over.
Unsurprisingly, he participated in his usual questionable antics by frantically rushing towards referee Andy Davis to question a decision of his, and duly earned himself an unnecessary yellow card.
Jeremy Ngakia - 3
A really tough evening for Ngakia was cut short at half-time when Valerian Ismael intervened and brought on Andrews in his place.
He was booked after hauling Clarke down early on in the game, and was ghosted past on more than one occasion as he struggled to contain the in-form Sunderland winger.
Ryan Porteous - 4
A lack of discipline and positional awareness meant Sunderland found it far too easy to slip balls down his side and exploit the space he so regularly left.
His booking after a lazy lunge opitimised his uninspiring performance and resulted in a free-kick for Aouchiche right outside the penalty area.
Wesley Hoedt - 3
A weak attempt to stop Huggins darting through and scoring the opener summed up why Watford's defensive errors are costing them dearly at the moment.
Hoedt could've been punished again in the second-half when his risky pass was intercepted by Aouchiche, who dashed towards goal and was only stopped by Bachmann.
Jamal Lewis - 5
After retaining his place from last weekend's game against Middlesbrough, Lewis didn't set the world alight with some poor set-piece deliveries and a lack of quality in the final third.
Francisco Sierralta - 5
Back in his holding midfield role, Sierralta looked lost at times.
Sunderland's midfield rotation caused problems for the Chilean as he was dragged into areas he visibly didn't feel comfortable in.
Imran Louza - 5
The Moroccan who potentially would've been heading to the World Cup in Qatar had it not been for injury, has been underwhelming so far this campaign.
His ability suggests he should be one of the best midfielders in the Championship, however his performances are stating otherwise after yet another lacklustre display saw him substituted when Watford were chasing a goal.
Tom Dele-Bashiru - 5
With Watford not having as much of the ball as usual, Dele-Bashiru struggled to have an impact on the game and was overrun in the centre of the park at times.
Tom Ince - 6
He received the ball reguarly when hugging the touchline, but failed to produce any real moments of quality which threatened the Sunderland defence.
His best moment came after cutting inside from the right to curl a shot straight into the grateful arms of Patterson.
Vakoun Bayo - 4
With a strike which could've landed all the way back in Hertfordshire, Bayo had a miserable evening.
Whilst you couldn't fault his work rate, his hold up play and finishing ability whenever he got his limited chances, were poor.
Giorgi Chakvetadze - 6
With his first start of the season, Chakvetadze managed to be Watford's main source of creativity in the first-half.
He pulled off some fancy flicks and crept into dangerous positions, but clearly lacked the confidence to convert.
He will be one of many players disappointed in themselves when watching Sunderland's first goal back, as the Georgian was beaten far too easily.
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Substitues
Ryan Andrews (Ngakia 45') - 4
His driving runs from full-back gave Watford's right-hand side some positive energy, however his controversial red-card put a dark cloud on an already bleak evening for the Hornets.
Yaser Asprilla (Tom Ince 45') - 6
The technical quality was there for all to see. His first touch was on the money and his work on the ball was imaginative, but the end result often resulted in wasted possession.
Ismael Kone (Dele-Bashiru 64') - 6
He came on during a difficult period of the game for Watford, but his effort to get on the ball and drive the team forward through his positive runs and intricate passing gave the midfield a different dimension.
Rhys Healy (Chakvetadze 65') - 3
In a cameo which featured him winning a free-kick after comically stumbling over thin air, Healy failed to impact the game in any positive way.
Mileta Rajovic (Louza 76') - 3
Despite being on the pitch for around 20 minutes, Rajovic hardly had a kick and was chasing shadows as Sunderland took control of the final stages.
