Two quickfire second-half goals from Ismaila Sarr and Troy Deeney handed Nigel Pearson his first win as Watford head coach as they beat Manchester United 2-0.
Sarr opened the scoring five minutes into the second half, with his shot slipping through the hands of David De Gea at his near post.
The winger was then fouled by Aaron Wan-Bissaka inside the penalty area only two minutes and 45 seconds later to allow Deeney to double the lead from the spot for his first goal of the season.
Ben Foster denied Man Utd substitute Paul Pogba and Marcus Rashford late on as bottom-placed Watford claimed a first home win of the season to move level with Norwich City in 19th on 12 points.
United sit eighth with 25 points after a first defeat in seven matches.
See: Watford report | Man Utd report
Next fixtures
Watford: 26 Dec v Sheff Utd (A)
Man Utd: 26 Dec v Newcastle (H)