Manchester United withstood a spirited second-half challenge from Watford to claim back-to-back victories and condemn the Hornets to their first defeat of the season.
United scored twice in three first-half minutes as Romelu Lukaku diverted Ashley Young’s cross in via his chest before Chris Smalling fired home Marouane Fellaini’s knock-down.
Watford pulled a goal back midway through the second half through Andre Gray, but despite putting Jose Mourinho’s side under heavy pressure for the final 20 minutes, they were unable to find an equaliser.
Nemanja Matic was sent off after a mistimed challenge on Will Hughes saw him pick up his second booking in the closing minutes, but United were able to hold on to claim their 15th victory over Watford in their past 16 meetings.
The result leaves Watford fourth, while United climb to eighth.