Troy Deeney’s late strike condemned Everton to defeat at Vicarage Road on Saturday evening.
The Watford skipper struck the decisive blow to hand his team victory in a tightly contested affair as both sides looked to close the gap on seventh-placed Burnley, who had drawn against Southampton hours before.
Manager Sam Allardyce made two changes to the team that started the last match – a 3-1 home victory against Crystal Palace – with Jonjoe Kenny and Ashley Williams coming in for the injured Seamus Coleman and Eliaquim Mangala.
With Leicester City and the Clarets both dropping points earlier in the day, Everton headed into the game knowing a win would take them level on points with Sean Dyche’s side ahead of next week’s meeting at Turf Moor.
The Blues started brightly and fashioned the first chance in the fourth minute.
Gylfi Sigurdsson floated a deep free kick towards the far post, where Oumar Niasse was lurking with intent. However, the Senegal international’s touch momentarily evaded him and his scuffed finish trickled harmlessly wide.
Niasse’s willingness to run into the channels was causing the Watford defence problems and he got in again moments later, this time bursting down the left before drilling in a low cross-shot that forced keeper Orestis Karnezis into a sharp save at his near post.
Looking refreshed after their warm-weather training camp in Dubai, the Blues were getting into some dangerous areas but they could not find the killer pass to take full advantage of their dominance.
In contrast, little was seen of Watford as an attacking force until former Everton wide-man Gerard Deulofeu tricked his way past Cuco Martina and burst into the area, but Michael Keane was alert to the danger, cutting out a low cross at the near post.
Midfielder Etienne Capoue then seized on a loose ball just outside the area but blazed his shot high and wide as Watford enjoyed their best spell of the half.
The Blues emerged for the second period determined to reassert their control, and they soon carved out a golden opportunity to break the deadlock.
Theo Walcott whipped a cross towards the far post, where Keane soared above his marker and directed a header back across goal for the in-rushing Tom Davies, but the ball agonisingly evaded the midfielder, who was inches away from marking his 50th Premier League appearance with a tap-in.
Sensing a precious away win was there for the taking, Allardyce replaced Niasse, who had put in another tireless shift up front, with January signing Cenk Tosun and the Turk quickly made his presence felt, shrugging off Deulofeu to win another corner.
However, it was Watford who stepped up a gear, and looked the more dangerous in the closing stages. Sub Kiko Fermenia tested Pickford with a low shot before the deadlock was broken on 79 minutes.
The Hornets seized possession in midfield, swept forward down the right and when the ball found Deeney in space in the box, he produced a powerful drive that left Pickford with no chance.
Allardyce introduced Dominic Calvert-Lewin and Yannick Bolasie for the final 10 minutes, with Sigurdsson and Rooney making way.
But it was Watford who could have extended the lead - Stefano Okaka forcing a very good save from Pickford.
The Everton gloveman was then in the opposite box for a last gasp corner - and it was his header that Tosun almost turned in but for Karnezis diving on top of the ball.
It proved the final act of a frustrating afternoon for the Toffees, who must now regroup ahead of their trip to Turf Moor in a week’s time.