Viktor Gyokeres scored the only goal of the game as Coventry City ended Watford's three-game winning run with a hard-fought victory against the high-flying Hornets at Vicarage Road.
Gyokeres' first-time finish moments after Ken Sema went close for Watford at the other end proved decisive in a game of few chances.
Ismaila Sarr was twice off target as Watford searched for an equaliser, while keeper Ben Wilson denied Joseph Hungbo a leveller in the last minute for a Hornets side who missed the chance to move back into the play-off spots.
Victory for Coventry, who only moved out of the relegation places on Tuesday when they upstaged another high-flyer in Blackburn, moves them up to 15th in the table.