Full-time score from Vicarage Road
Millwall's awayday blues continued as The Lions' 10-men were soundly beaten by a Watford side that recorded their first goals - and points - at Vicarage Road in six games.
There was a distinct lack of festive cheer for the 963 travelling Lions fans, who suffered as their team were beaten for the seventh time on their travels this season, during which 33 goals have been conceded.
Manager Steve Lomas made five changes to the side beaten at home by Middlesbrough, fielding a new-look defence that included Danny Shittu, Shane Lowry and Justin Hoyte whilst Jermaine Easter returned to the team with Guy Moussi making a rare appearance following his loan move from Nottingham Forest.
The Millwall boss had demanded a response following the woeful display against Boro last weekend, but his hopes of a positive reaction were dented within 10 minutes of this Boxing Day game when Shittu, playing against his former club, was sent off for a challenge on Troy Deeney, who then rubbed salt into the wounds by slamming home the resulting penalty kick past keeper David Forde.
Lomas' hopes of getting anything from this match were all but destroyed by the 26th minute when Forestieri doubled Watford's tally, capitalising on some poor defending to fire home from 12 yards after The Lions had made a mess of clearing their lines.
It could have been even worse for the visitors in a forgettable opening first 45 minutes as Marco Cassetti sent a free header over the bar following a deep delivery into the danger zone with the Millwall backline again stretched.
The half-time whistle couldn't come quick enough for Millwall, but within three minutes of the restart Watford had further increased their lead when left-back Anya was allowed time and space to cut in from the left before hitting a rasping shot that flew past the stranded Forde.
Millwall did get the ball in the back of the net moments later, only for Steve Morison, who worked tirelessly up front, to see his close-range header ruled out for off-side.
Matters went from bad to worse for Lomas' charges just before the hour-mark when Robinson was harshly penalised for handball and this time Lewis McGugan stepped up to sweep the ball into the bottom right corner for Watford's fourth goal of the afternoon.
Only the woodwork spared Millwall's blushes further as the home side rattled the bar three times as they cruised to three points - and leave The Lions perilously close to the relegation zone.
Watford: Almunia, Doyley, Angella, Ekstrand, McGugan (Battocchio, 76mins), Forestieri, Murray, Anya (Bellerin, 84mins), Cassetti, Thorne (Iriney, 69mins), Deeney. Subs not used: Bond, Fabbrini, Smith, Nosworthy.
Bookings: Forestieri (45mins), Ekstrand (69mins)
Scorers: Deeney (9mins, pen), Forestieri (26mins), Anya (48mins), McGugan (60mins, pen)
Millwall: Forde, Hoyte, Lowry, Abdou, Shittu, Beevers, Trotter (Smith, 61mins), Moussi (Robinson, 10mins), Woolford, Morison, Easter (Chaplow, 55mins). Subs not used: Bywater, Dunne, Malone, McDonald.
Sent off: Shittu (9mins)
Bookings: Chaplow (64mins), Lowry (78mins)
Ref: A D'Urso
15,471 (away 963)Att: