Ole Gunnar Solskjaer and his side will be hungry for a win after two straight defeats in the league before the international break, and especially as his first Premier League clash since being appointed Manchester United's permanent manager.
Javi Gracia's side, on the other hand, have enjoyed a decent run of form in the lead up to this match although the Watford boss felt that five changes were necessary ahead of Saturday's encounter, bringing in the likes of Foster, Janmaat, Kabasele, Britos and Masina.
Five changes might have seemed excessive but it seemed to work for Watford as they looked to be the most likely to score of the two teams inside the first 15 minutes. Crosses were coming in from both flanks and United's defence were tested right from the get-go.
Unsurprisingly though, that didn't last too long and it was up to Luke Shaw to set up Marcus Rashford for United's opening goal. A delicious through ball set up the youngster nicely who proceeded to slot it past an approaching Ben Foster.
It was from this point onwards that United managed to find some rhythm of their own and it was Watford's defence who were sent scrambling. Britos and Janmaat were put to work to try and keep the likes of Rashford and Martial at bay.
The Frenchman passed up Man United's closest chance to claim a second after his shot was blocked from point blank range by Foster. The corner came in whose rebound found itself at Martial's feet. He didn't have much time to think before getting the shot away but Foster was in the right place at the right time, much to Watford's relief.
The visitors managed to keep United mostly at bay for the remainder of the first-half, as we approached the break. Javi Gracia had a slightly concerned look on his face and will have welcomed the break for his side to regroup.
Much like the first-half, Watford claimed most of the possession at the restart with Janmaat and Pereyra both claiming Watford's first two shots on target. Manchester United really struggled for possession as Watford were relentless. Especially down the left wing with Hughes. Again, it was just their final touch which let them down.
Capoue's shot in the aftermath of a Watford free-kick summed up their match. Numerous attempts on goal, significantly more than United, but nothing threatening de Gea.
Manchester United punished Watford's inability to capitalise on their possession with a second goal thanks to Anthony Martial. Solskjaer's men only needed two minutes of possession to damage Watford's hopes of an equaliser.
Watford will have felt hard-done-by as the replay showed Martial was offside, as well as possibly fouling Ben Foster while scrambling to stab the ball over the line.
In doing so, the Frenchman was injured and subsequently brought off for Rojo. Watford would have to pull something miraculous out the bag for a win with just over 10 minutes of regulation time remaining.
It was Manchester United's game to lose at that point and they very nearly jeopardised their lead allowing Watford back into the match late on.
Doucoure scored a late goal in the aftermath of a Watford free-kick but with just three minutes of added time, there wasn't enough time for an equaliser and it ended up being a consolation goal.
Watford will have left Old Trafford fairly pleased with their performance and ability to deny Manchester United possession. But ultimately, it was Solskjaer's side who made the most of their chances to claim a much-needed victory at home for Solskjaer's first match as permanent manager.
United now sit fourth in the Premier League table, which would guarantee them a Champions League spot for next season if they can stay there. Arsenal are hot on their heels however with a match on Monday against Newcastle.