Barnsley have dented Watford's promotion hopes and boosted their battle against relegation from the Championship with a narrow 1-0 victory at Oakwell this afternoon.
Gianfranco Zola's side are the top scorers away from home in the Championship and made a bright start when Ikechi Anya caused panic in the Barnsley backline.
Rory Delap was forced off injured after just five minutes for the Tykes and replaced by Bobby Hassell.
Matej Vydra fired well over before Lloyd Doyley stopped Jason Scotland from pouncing at the other end.
The Tykes took the lead 10 minutes before the break when Hassell climbed highest to meet a precise delivery from Jacob Mellis at the far post.
Watford were unable to respond in a frantic final passage of play as Barnsley held firm to take a narrow advantage into the second half.
Troy Deeeney went on the attack straight after the break for the Hornets but was penalised for a lunge on Luke Steele.
Chris O'Grady came close to putting the result beyond doubt soon after, cutting inside to beat two defenders before forcing Jonathan Bond to make a smart save.
Fernando Forestieri was thrown on midway through the second half but despite a prolonged spell of possession Watford slipped to an unlikely away defeat.