After a goalless first half, the hosts took the lead in the 59th minute when Miguel Britos jumped highest to head the second half victor.
That added incentive to keep producing his top form can only work in the Black Cats' favour, but as they attempt to haul themselves off the foot of the table, Moyes knows even his 14-goal hitman cannot do it by himself.
A second-half goal from Miguel Britos earns Watford a 1-0 victory over struggling Sunderland at Vicarage Road.
But the biggest positive came from the bench as Lee Cattermole returned to the squad for the first time since September. His header was powerful but somehow deflected on to the bar by Fabio Borini. The pick of them came when he dived full-length to scoop Doucoure's shot over the crossbar.
The fourth loss out of the last five for the Black Cats surely sentences the side to what seems their inevitable fate of relegation to the Championship.
Watford started to create the better of the chances, with Etienne Capoue sending a shot just wide from distance, before Pickford was required to turn behind Niang's rasping effort.
Efforts continued to rain down on Pickford's backline before the interval with Capoue and Niang letting fly, but the Hornets were dealt a blow on 42 minutes as Younes Kaboul limped down the tunnel to a standing ovation from the red and white army.
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Adnan Januzaj nearly managed to sneak the ball past Heurelho Gomes in the opening 10 minutes with a cross-turned-shot, as Younes Kaboul opted to leave it for his keeper only for Gomes to scramble across goal to tip it wide.
Isaac Success entered the fray soon after and he nearly opened the scoring in spectacular fashion, letting the ball drop out of the sky before volleying inches wide of the target.
The Sunderland goalkeeper was busy - as usual - and made some fine saves to thwart Watford in the first half.
Within the space of three minutes he picked out Januzaj on two occasions, but the first was charged down and the second forced a simple stop from Gomes. Walter Mazzarri, for his part, insisted his team had never been part of a relegation scrap.
Sunderland rallied in the closing minutes - with Gomes denying a well-struck effort by Borini from the edge of area, however it was yet another case of what might have been for David Moyes - who again showed his lack of tactical ambition.
Pickford; Jones, O'Shea (c), Kone, Oviedo; Denayer, Gibson (Ndong, 62'), Rodwell, Borini, Januzaj (Khazri, 70'); Defoe.