A brace from captain John Eustace secured Watford three points against Barnsley at Vicarage Road.
Eustace gave his side the lead when he acrobatically hooked in Sean Murray's deflected cross on 32 minutes.
He doubled their advantage midway through the second half, picking up a clearance and breaking through the Barnsley defence before sliding home.
Tykes debutant Scott Golbourne ensured a tense finish when scored from close range with five minutes to go.
Watford had dominated early proceedings, with Joe Garner feeding Troy Deeney whose shot was charged down.
Eustace curled a shot narrowly wide before his spectacular effort went in off the post to give the Hornets a first-half lead.
Barnsley improved in the second-half, Andy Gray headed wide before Jim McNulty's free-kick was tipped over the bar by Scott Loach.
McNulty had another excellent chance to draw his side level, heading over unmarked from David Perkins's cross.
But Eustace put his side in the driving seat shortly afterwards, before Golbourne turned in Scott Wiseman's cross at the far post to set up a dramatic finale.