Ole Gunnar Solskjaer’s side, unbeaten in four league games under the new boss, could move level on points with fifth-placed Arsenal with a Wembley win.
The squad have been boosted by the return of Paul Pogba from injury, with the talismanic Frenchman making the journey south.
Playmaker Juan Mata, who is out of contract at the end of the season, stopped for a selfie with a waiting fan.
The team train was due to arrive in Watford at around 5:00pm, before the squad boarded a bus to finish the journey to their Wembley Hilton hotel.
Solskjaer’s men were earlier boosted by the presence of Sir Alex Ferguson at the club’s Carrington training base.
The former boss was believed to have observed the first-team’s final training session before their match against Tottenham.
Ferguson has become more visible around the club following the departure of Jose Mourinho in December.
A club legend, Ferguson was believed to have been involved in the decision to appoint his former player Solskjaer and old No 2 Mike Phelan until the end of the season.
Reports even claim that Ferguson even delivered a rousing speech to the squad during the Christmas period.