A first-half strike from Marnick Vermijl has guided Preston North End through to the next round of the League Cup at the expense of Premier League side Watford.
The home side took the lead in the eighth minute when Vermijl latched on to a loose ball in the area from Josh Brownhill's deflected shot and slotted the ball under Giedrius Arlauskis.
Watford came into the game as Nathan Ake raided down the left flank and put a low ball across the face of goal, but Matej Vydra could only fire his volley over the bar.
Fernando Forestieri had the chance to bring his side level when Watford were awarded a free kick in the edge of the box, but his strike sailed over the bar.
The visitors came close just before the break when Miguel Layun lined up a strike from distance, but his effort sailed inches over the crossbar.
Simon Grayson's men came close to adding a second goal when Neil Kilkenny fired a low volley towards the bottom corner, but Arlauskis palmed the ball to safety.
Preston threatened once more as Kyel Reid beat two defenders down the left before curing an effort towards the bottom corner, but his strike went inches past the post.
Quique Flores's evening became worse when Miguel Britos was sent off for the visitors for violent conduct for an apparent elbow against a Preston player.
The Hornets pushed for a late leveller, but the hosts held firm to ensure that the Premier League side crashed out of the competition.