Victory saw Watford climb to ninth in the table but the result condemned northeast side Middlesbrough to a fourth defeat in five league matches.

Greece international Holebas's goal was a rare highlight in a largely uninspiring contest where referee Roger East turned down several penalty appeals of varying merit at the Riverside Stadium.

Middlesbrough had the greater share of possession in the first half but rarely threatened the Hornets' goal.

Stewart Downing fired a third-minute half-volley over the crossbar and Gaston Ramirez dragged a shot wide.

Middlesbrough's Alvaro Negredo had a penalty appeal rejected as he went down under the combined challenge of Younes Kaboul and Nordin Amrabat, who was fortunate to escape punishment for grabbing hold of his opponent's shirt.

Moments later, Boro had a far less convincing penalty shout when Downing headed against Amrabat's arm from point-blank range before firing the rebound wide of goal.

Boro defender Ben Gibson tried his luck with a 35-yard shot but the match was still goalless come half-time.

The home side appealed unsuccessfully for a penalty early in the second half when Negredo went to ground following a challenge by Holebas.

At the other end of the pitch, Holebas gave Watford the lead in some style when, having latched onto Marten de Roon's clearance, he smashed a fierce shot high into the top corner and beyond stunned goalkeeper Victor Valdes.

Ramirez had another penalty appeal turned down after falling to the turf following a clash with Miguel Britos eight minutes later, and in the closing stages it was Watford who almost grabbed the game's second goal when a shot from Isaac Success was saved by Valdes.