Manchester United closed the gap at the top of the Premier League to five points after coasting to victory at Watford on Tuesday night.
Ashley Young was the unlikely hero for the visitors, scoring twice in the opening 45 minutes - including a superb free-kick from long-range.
Anthony Martial made sure of the points shortly after the half-hour mark as Jose Mourinho's side made light work of Marco Silva and Co before half-time.
The hosts rallied in the second period and finally got themselves on the scoresheet 13 minutes from time when Troy Deeney converted from the penalty spot following Marcos Rojo's clumsy foul.