Watford suffered their first home defeat of the season as Plymouth Argyle moved off the foot of the Championship table with a 2-1 win.
The hosts started brightly and created their decent opportunity in the fourth minute when John-Joe O'Toole's ball across the area just evaded Tamas Priskin in the middle.
Argyle slowly came into it, though, and went ahead on the half-hour mark when Karl Duguid volleyed Rory Fallon's lay-off into the corner from 15 yards.
Will Hoskins lashed wide from four yards when he should have scored in the 54th minute and Watford were made to pay 18 minutes from time when Jay DeMerit handled in the box to allow Luke Summerfield to drill into the bottom corner from the spot.
Paul Gallagher headed against the bar but O'Toole turned home a Tommy Smith shot in the 83rd minute to set up a tense finish.