The travelling Hornets are already safe from the drop and coach Javi Gracia will be hoping to finish the campaign positively despite a potentially uncertain summer ahead.
United sign off on the final day having already secured second place in a season that has arguably been one of relative stasis, despite Jose Mourinho's remonstrations that the club's standing in the league represents evident progress.
Second place does not lie and United are evidently the second-best squad in the league after 37 games, but that does get away from the fact that Mourinho's side are 19 points behind champions Manchester City, who ran away with the title at a canter under Pep Guardiola.
Mourinho has insisted that Guardiola has had a headstart on his United project and those claims therefore establish next season as a term in which the Red Devils must provide a more worthy challenge to Guardiola's marauding Sky Blues.
On paper making the step is an easier one with United's financial wealth, although as this term has showcased, money doesn't necessarily buy what you need to consistently challenge at the highest level, both domestically and in Europe.
The summer window will be an intriguing one for United fans, as they prepare to find out what exactly the future holds for mercurial talents Paul Pogba and Anthony Martial. Will Mourinho relent and move away from the ingrained pragmatism that appears to be stifling his most talented players? Or will he phase them out in favour of more adaptable performers?
United were poor during their defeat to Brighton & Hove Albion last weekend, and that game provided a perfect example of just how inconsistent this United side have been during the campaign. Eight changes against West Ham United and a slight tactical shift appeared to do little better for Mourinho on Thursday, as the Red Devils laboured to a mind-numbing goalless draw with the Hammers.
That said, United still have a trophy to play for in the shape of the FA Cup, and Mourinho will be keen for his side to find some form ahead of the meeting at Wembley. In the 500th Premier League match at Old Trafford, United have the perfect opportunity to pick up three points against a stuttering Watford.
The Red Devils have won 13 of their last 14 meetings with the Hornets across all competitions. The only defeat coming at Vicarage Road in September 2016.
Recent form: WLWWLD
Recent form (all competitions): LWWWLD
The Hertfordshire club finally limped to confirmed safety last weekend when they overcame a resurgent Newcastle United at Vicarage Road.
Having started the campaign so fruitfully under Marco Silva, in which the Hornets went unbeaten in their first eight games, the manner of peaks and troughs since the arrival of Gracia has probably have left Watford fans wondering what might have been had Silva not had his head turned by other clubs earlier in the season.
The club's 2-1 win over Newcastle last time out proved to be Watford's first league victory in seven games since beating relegated West Bromwich Albion back in March. During that seven-game run, Watford conceded 15 goals and scored just three.
Across 37 games, Watford have won 11, drawn eight and lost a problematic 18 contests in a beleaguered record that would have surprised many considering the club's rampant start in the Premier League.
It remains to be seen how exactly the Watford board are viewing progress under Gracia, and the manner in which Hornets officials have moved on previous coaches will not leave the Spaniard in the most confident of moods heading into the summer.
The second half of the campaign has not been the most impressive for the club, although Watford have clearly unearthed a gem in midfielder Abdoulaye Doucoure. The 25-year-old Frenchman has produced a string of impressive displays in yellow and has since attracted transfer interest from some of Europe's elite clubs.
Roberto Pereyra has also enjoyed a bright spell of form at the back-end of the campaign. The Argentine has now scored three in his last five despite having notched just two goals in 29 appearances beforehand.
The Hornets have never actually won a league game at Old Trafford, and they head north on Sunday having failed to score in eight away matches. Added to that, Watford have lost every one of their trips to sides in the top six this term. During those meetings the Hornets have scored only three but conceded 17.
Recent form: DLLDLW
Mourinho has confirmed that Michael Carrick will start in what will be his last game as a player at Old Trafford before he takes up a coaching role next term.
United will also hand returns to forwards Marcus Rashford and Martial, who were left on the bench for Thursday's draw with West Ham.
Manchester United possible starting lineup:
Romero; Darmian, Bailly, Jones, Shaw; Carrick, Matic, Pogba; Martial, Rashford, Mata
Watford possible starting lineup:
Karnezis; Janmaat, Cathcart, Kabasele, Holebas; Hughes, Doucoure, Capoue, Pereyra, Gray, Deeney
Head To Head
The clubs have met nine times in the history of the Premier League. United have won eight of those meetings and the Hornets have won once.
In the reverse of this fixture earlier in the campaign, United claimed a 4-2 win at Vicarage Road, despite Watford offering some late resistance through Troy Deeney and Doucoure.
United hold the upper hand in all competitions, winning 13 of their last 14 meetings. Watford's only Premier League win over the Red Devils came in 2016.
We say: Manchester United 2-0 Watford
United have looked flat in recent weeks and Mourinho will be urging his players to show him something ahead of the FA Cup clash with Chelsea at Wembley.
A good number of United players still have a lot to prove ahead of what could be another busy summer window at Old Trafford - Mourinho has already hinted at making improvements when the market reopens.
Watford come into the away trip with the pressure off and safety secured, potentially leaving the Hornets with an opportunity to take the game to a stuttering United side.