Andre Gray pulled one back for Watford with a superb finish
The Watford striker planted a sweet strike past David De Gea in goal.
Gray, 27, arrived onto Abdoulaye Doucoure's cut-back to the edge of the area, before placing a powerful side-footed finish high into David De Gea's net.
The keeper got his fingers to the shot, but it wasn't enough to stop it.
The goal came against the run of play in the second half, as Manchester United attempted to consolidate their two goal lead at Vicarage Road.
Gray has now scored 6 goal in 33 appearances for Watford.