John Eustace had a goal disallowed deep into injury time, as former Hornets boss Brendan Rodgers secured revenge.
Swansea edged 2-0 in front thanks to goals from Scott Sinclair and Stephen Dobbie, before on loan striker Frank Nouble made it 3-0 to the Swans on 69 minutes.
Watford then gave the home faithful a glimmer of hope, substitute Troy Deeney netted his first league goal in a yellow shirt, Martin Taylor also pulled a goal back for the home side, but that wasn’t enough as Swansea secured their first away win of the season.
Sinclair edged the visitors ahead inside 15 minutes; Swansea’s first real attack of the match was finished off by the former Chelsea man, as he converted home via a Dobbie assist.
Dobbie then made it 2-0 with a cracking finish, as his sublime effort from just inside the 18 yard box deflected kindly off the bar and into the net, that proved to be Dobbie’s fourth goal of the season.
Watford centre back Adrian Mariappa could of well clawed a goal back for the Golden Boys, his diverted header was cleared off the line by Swansea defender Alan Tate.
At that point Swansea were sitting in a comfortable position, the team from Wales were well on course for all three points and there first away win of the season.
69 minutes into the second half and the visitors made it three, great play by winger Nathan Dyer set the ball on a plate for Frank Nouble, the on loan West Ham striker slotted home from close range to score his first goal for Swansea.
Just after 70 minutes the home side pulled a goal back, after Rodgers decided to substitute the on form Scott Sinclair.
Substitute Deeney first had a shot blocked by Swansea defender Angel Rangel, a minute later Deeney fired home with a perfect finish. The former Walsall man had yet another chance, Jordan Mutch set up the goods this time; however Deeney couldn’t convert.
84 minutes gone and Watford scored their second of the game, Malky Mackay’s risk of sending Martin Taylor up front proved to be the rightful decision, the defender himself headed home from a Doyley cross.
Watford was pressing Swansea City in the final stages, as the team from Hertfordshire went in search for an important equalizer.
In the final minute of the game the linesman decided to flag John Eustace offside, the midfielder saw a last gasp goal ruled out. Watford still remain in the play-off places while Swansea move up a place to eighth.
After the game the fans expressed their frustration at Brendan Rodgers; however the Swansea boss remained calm. “The Supporters were fine, the guys will tell you here I had a real close relationship with people – the media, the players, the people – so I understand the frustration”
It was a spirited fightback from the Hornets, but they just couldn’t manage to secure four consecutive wins in a row. Watford’s next task is away to Sheffield United, while Swansea host East Midlands side Derby County.