Swansea overcame a poor away record with a convincing 2-0 victory at Vicarage Road that damaged further Watford's fading promotion push.
The Welsh side had picked up just three points out of a possible 18 on the road under new manager Vitor Matos, but were convincing winners with goals from Marko Stamenic and Josh Key.
Watford, by contrast, have not won a Championship match since New Year's Day and played the final four minutes of injury time with 10 men after Nestory Irankunda was sent off for pushing Liam Cullen to the ground.
Much of the first half was consumed by the tactical battle formed on the Iberian peninsula. Since Portuguese Matos arrived in south Wales, he has placed an emphasis on the rapid, high press that he once employed on Jurgen Klopp's staff at Liverpool.
For 15 minutes, Watford could not cope with the white shirts that swarmed around them until the home side's Spanish manager Javi Gracia clearly signalled to his players to play over the Swansea press.
That ploy gave Watford the room to attack at pace. They forced a number of openings, with Othmane Maamma prominent. The winger fed Marc Bola whose low shot was saved by the legs of Lawrence Vigouroux.
Vigouroux then rushed out to deny Maamma before plunging to his right to hold onto a low Tom Ince shot.
At the other end, the home side knew they had to be wary of the Championship's leading scorer Zan Vipotnik.
The Slovenian suddenly found himself in space in the 40th minute, but after swivelling, his connection on a left-foot shot was not sweet enough to beat Watford keeper Egil Selvik.
Ince almost broke the deadlock in the opening three minutes of the second period, cutting inside to unleash a left-foot shot that missed the far post by inches.
Instead, it was the visitors who took the lead after 55 minutes. Josh Tymon's corner was headed on by Vipotnik and stabbed home by Stamenic at the far post.
It required a fine save at full stretch by Selvik to prevent Goncalo Franco from increasing Swansea's lead six minutes later.
Watford offered little in response save a Luca Kjerrumgaard shot on the turn and a header, both of which were comfortably saved.
The difference between the sides was obvious when substitute Key made it 2-0 in the 80th minute. Stamenic won the ball outside the Watford area and then forced his way through two ineffective tackles before his cross-shot was turned home by Key.
As Watford's frustrations grew at their inability to change the course of the game, Irankunda pushed Josh Tymon in the chest. That drew a similar response from Cullen on the Australian only for Irankunda to push Cullen with two hands in the neck.
Watford's Javi Gracia:
"I know that my job is to prepare the players during this busy schedule. It's a demanding league. Some players are injured and we don't have many other options playing.
"We try to manage this situation, but what we are doing on the pitch and off the pitch at the moment is not enough.
"I want to speak to the owners about everything, what is happening in the future, everything. We have to know clearly where we are going.
"I want to speak to them today if I can. I think that you have to do things as soon as possible."
Swansea's Vitor Matos:
"We started with good aggression but Watford took control and pushed us back, which hasn't happened a lot since I have been here. Watford have a really good team and a really good squad as well.
"But we coped, we suffered together as a team and then in the second half we were able to score when we created chances. I think that was the key.
"The foundations are getting settled. We need to keep performing like we have been and to be clinical and efficient. And to have a little bit of luck at the right moment. Score with the right opportunity at the right moment."
