Ole Gunnar Solskjaer got his tenure as permanent Manchester United manager off to a winning start at Old Trafford.
Solskjaer was confirmed as Jose Mourinho's successor this week and welcomed Watford on Saturday.
The visitors were the better side for the first half but United hit them on the break to open the scoring.
Luke Shaw did excellently in the build-up before Marcus Rashford fired into the net.
Anthony Martial confirmed the win for United after the break to boost their top four chances before a late Abdoulaye Doucoure winner.
Here are Mirror Football's complete ratings from Old Trafford as Solskjaer secured a key victory.
Victor Lindelof's Man Utd absence explained by Ole Gunnar Solskjaer
Manchester United
De Gea 8 - A number of fine saves to keep Watford at bay
Young 6 - United's veteran skipper didn't put a foot wrong.
Jones 6 - Dealt with Deeney well in the absence of Lindelof
Smalling 7 - Solid performance in central defence. Some key blocks
Shaw 8 - Did excellently to set up Rashford for United's opener
Matic 6 - Proved his fitness and remains a key cog in this United side.
Herrera 6 - Puts the hard yards in. United can't afford to let him go.
Pogba 6 - Pretty ineffective display from midfielder amid Real Madrid speculation
Mata 7 - Linked play up well. Adds something different to United side
Martial 7 - Back in the team and back among the goals
Rashford 8 - Took his chance once again. Turning into a lethal striker.
Subs
Lingard 7 (for Mata, 63)
Pereira 6 (for Herrera, 63)
Rojo (for Martial, 77)
Watford
Foster 6; Janmaat 6 (Femenia 55, 6) Kabasele 6, Britos 6, Masina 6; Doucoure 6, Capoue 6, Hughes 6 (Success 81 6), Pereyra 7; Deulofeu 7 (Gray 73, 6), Deeney 7.
Unused subs: Gomes, Cathcart, Quina, Holebas.
