Jose Mourinho’s men are sure to finish second in the league this season, albeit at least 16 points adrift of neighbours Manchester City.
The Hornets have claimed just a single point from the last available 33 on the road, but can be backed at 8/1 (9.00) to finish on a high note by pulling off a shock win here.
United were held to a 0-0 draw at West Ham on Thursday, and you can get odds of 19/4 (5.75) on them being forced to settle for a point yet again.
Romelu Lukaku is ruled out for this clash as he looks to recover in time for the cup final, although Marouane Fellaini will hope to be involved after shaking off a muscle injury.
Meanwhile, Javi Gracia is likely to be without all of Andre Carrillo, Stefano Okaka, Tom Cleverley, Nathaniel Chalobah, Younes Kaboul and Tommie Hoban.
Strong United backline
However, even their sternest critics could not deny their impressive defensive record, particularly on home turf.
Mourinho’s men have conceded just 28 times in 37 league fixtures this campaign, letting in a league low of nine goals in 18 matches in their own back yard.
Considering Watford have found the net just twice and picked up a single point in their last 11 away league matches, odds of 11/10 (2.10) seem generous on United coming out on top while keeping a clean sheet on Sunday.