After a goalless opening 35 minutes at Vicarage Street, United stamped their authority on the Premier League fixture with two targets in three minutes.
First, Belgium striker Romelu Lukaku bundled the ball residence from Ashley Younger’s inviting cross to provide the Crimson Devils the lead.
Marouane Fellaini performed a component within the opener and was additionally instrumental in United’s second objective, heading the ball to Smalling from a nook.
England worldwide Smalling nonetheless had work to do however managed the ball together with his chest earlier than swivelling and volleying previous Ben Foster.
Watch Rio Ferdinand’s response to the objective:
Chatting with BT Sport at half-time, former Manchester United and England star Ferdinand mentioned: ‘Fellaini is a menace in that space. It’s an ideal end from Chris Smalling.’
Former Watford midfielder Derek Payne, in the meantime, advised BBC Radio 5 Dwell: ‘Actually good end from Smalling, centre half ending like a centre ahead.
‘He does ever so properly, chests it, turns and smashes it previous Foster.
‘Watford asleep to the second ball, for those who don’t win the primary ball you’ve obtained to win the second.’
Manchester United are chasing back-to-back Premier League victories after beating Burnley previous to the primary worldwide break of the season.