Manchester United came in to the game looking to build on their win against Burnley in their last fixture, while the home side were tipped by some to make Jose Mourinho's start to the season even worse given the excellent from they had showed in the first four encounters of the season.
The game started extremely openly, with both teams showing attacking intent in the first 20 minutes, with Romelu Lukaku almost scoring on a couple of occasions.
However, Lukaku managed to break the deadlock in the 38th minute of the game in somewhat controversial fashion.
The ball came in to the box from an Ashley Young cross, and while Lukaku seemed to be offside according to the Watford players that flag didn't go up and the Belgian put the ball past a diving Ben Foster.
September 15, 2018
The Watford keeper had made a string of excellent saves in the first period, perhaps the best coming from a Paul Pogba volley that the ex-West Brom keeper managed to keep out with an excellent reaction stop.
However, he could do nothing to keep the second goal out which came just four minutes before the break, as Chris Smalling controlled a Fellaini knock down and swivelled to smash the ball in to the roof of the net.
The home side came out fighting in the second half as they looked to maintain their perfect start to the season, with Troy Deeney drawing a good save from De Gea early in the second period.
On 65 minutes the 'Hornets found the goal they had been looking for, as the ball was drilled in from the left hand side and found Andre Gray who was waiting on the edge of the box to put the ball in to the top corner of the net impressively.
September 15, 2018
The home side kept pushing for a winner but United defended resolutely, and bar a Nemanja Matic sending off for a second bookable offence just before the final whistle, Mourinho will be happy.
Paul Pogba was particularly impressive in midfield as he combined his typically accurate passing range with excellent hold up play and even ventured in to the box a few times, while Romelu Lukaku worked tirelessly up front.
Javi Gracia has positives to take from the game too, depsite losing their 100% record this season, as his side showed a huge amount of spirit to try and push for the second goal, particualrly through Troy Deeney and Will Hughes, but the 'Red Devils' proved just too clinical for them on the day.