Hendrick, the club's £10.5million record signing in the summer, nodded home Steven Defour's 38th-minute corner and the Belgian bagged a second assist when Keane rose to head a second shortly after half-time.

Defour has now scored one and set up three of Burnley's five goals this season, and here provided the kind of spark that was visibly lacking from the visitors, who suffered a sharp comedown having turned over Manchester United last time out.

For the Clarets it was a welcome second win of the campaign, following their surprise defeat of Liverpool, while the visitors may wish to write off their trip to Lancashire as a bad road trip.

They were passengers in the first period, allowing Burnley's industrious midfield to over-run them.

Walter Mazzarri tinkered with his 3-5-2 formation early on, reverting to a back four with Valon Behrami picking up the extra defensive duties.

The Clarets had all the territory and all the meaningful possession but, until Hendrick intervened, few clear chances.

Hendrick and Johann Berg Gudmundsson were the likeliest threats, the Irishman always lurking in the space behind Sam Vokes while the Icelander served notice with a couple of tempting crosses.

Vokes won a corner from one Gudmundsson delivery and when that was half-cleared George Boyd stung Heurelho Gomes' palms with a snap shot.

Gudmundsson also lashed a 25-yard drive wide of the near post but Watford, despite regular panicky clearances and under-hit passes, were hanging in.

The away end looked to lift things by launching a "Troy Deeney for England" chant but their captain was feeding on scraps.

He had only one real opportunity and was denied at the near post by Three Lions squad man Tom Heaton.

A corner at least allowed Watford to show off a routine that ended in a sweetly-struck Jose Holebas volley but Claret shirts blocked the shot and its follow up to sustain the stalemate.

Half-time was beckoning when Dean Marney intercepted a stray Gudmundsson shot and nicked a corner, allowing Defour to take aim from the right.

The Belgian aimed for Hendrick, who outmuscled Holebas to force his header over the line.

Watford seemed to think Defour's cross had drifted out on its way into the box but there was no reprieve.

The only recriminations about Burnley's second, five minutes after the restart, were aimed at defenders rather than officials.

After another Defour corner had come back to him the midfielder crossed again, with Watford this time allowing Keane to climb above them and direct the ball home.

Burnley's desire was laudable but they were up against the most benign defence imaginable.

Defour attempted to add a goal to his pair of assists on the hour, working Gomes from 20 yards - an effort the Brazilian could only beat away in self-defence.

Watford did little more than hint at a comeback, Isaac Success sliding a shot across goal after burrowing in on the left and Behrami volleying wide.