Goals from Andreas Voglsammer and Zian Flemming either side of half-time succumbed 10-man Watford to Boxing Day defeat, as Millwall edged a hard-fought festive encounter 2-0 at Vicarage Road.

Gary Rowett’s Lions started on the front foot and earned the advantage when Voglsammer struck 22 minutes in, before a João Pedro injury and a Hassane Kamara red card increased the scale of the Hornets’ task.

With the numerical advantage Millwall fashioned a number of opportunities after the interval, and though Ismaïla Sarr and Keinan Davis led the home charge for an equaliser, away top scorer Flemming made it 2-0 late on.

Watford remain in the play-off mix despite a first loss since the visit of Coventry City in early November, and Slaven Bilić’s men will be eager to quickly bounce back to winning ways away at Swansea City on Friday evening (December 30, 7.45pm KO).

Head Coach Bilić named an unchanged XI following the 2-0 win on the road at Huddersfield Town last time out, while forward Samuel Kalu made a welcome return to the substitutes’ bench after recovering from injury.

Watford were forced to defend within the game’s opening minute, with a cleverly-worked Millwall throw-in serving up a chance for Flemming to whip a dangerous cross into the box, though Jake Cooper just couldn’t quite stretch to meet the ball at the back post.

Flemming himself sent a speculative effort towards Daniel Bachmann’s goal moments later, as the Lions looked to gain an early advantage, and the latter then recovered well to deny Tom Bradshaw from notching the opener after his initial clearance went straight to the visiting striker.

Referee Josh Smith waved away home penalty appeals just after the 10-minute mark, when Davis was felled by Murray Wallace, but Millwall were soon back on the attack at the other end with a succession of corners that ultimately came to nothing.

Austrian stopper Bachmann had to be alert to keep out a piercing George Saville drive from the edge of the box, as another Flemming long throw caused the Hornets plenty of problems, before the home defence did well to win a free-kick in the aftermath.

But it wasn’t long before the Londoners did take the lead at Vicarage Road, with Voglsammer coolly finishing past Bachmann in the 22nd minute after Bradshaw beat Craig Cathcart to the ball and teed up the former Germany youth international.

Voglsammer could have had a second five minutes later, if not for another strong reaction save from Bachmann, and the subsequent corner saw skipper Shaun Hutchinson send a looping header over the bar.

Concern spread among the Watford supporters when Saville caught João Pedro with a nasty challenge close to the half-hour, with the Millwall midfielder earning a yellow card as a result, but with 10 men on the field temporarily Watford nearly grabbed an equaliser when Jeremy Ngakia headed at George Long.

Despite attempting to run off his knock, João Pedro was forced off for Yáser Asprilla 11 minutes before half-time, and Watford’s afternoon was soon made even more difficult when Kamara was shown a straight red card for his reaction to a Danny McNamara challenge.

Bilić made his second change of the afternoon at half-time, with William Troost-Ekong replacing Leandro Bacuna and dropping into a back three, but Millwall continued where they had left off with the first chance of the second half, though Bradshaw was stopped by the offside flag.

A string of away corners ensured that the pressure remained on the Hornets’ defence, and with 53 minutes on the clock Millwall’s Cooper flashed a tame header past Bachmann’s left-hand post.

Saville was the next man in blue to try his luck, though his long-range shot wasn’t powerful enough to trouble Bachmann, and then Voglsammer came within inches of doubling his tally when his lofted effort clipped the crossbar.

The Golden Boys weren’t ready to lie down however, and a last-ditch Cooper interjection was required to prevent Sarr getting his shot off on the turn, after the Senegal star was neatly picked out by Christian Kabasele.

That Sarr chance seemingly provided some new-found optimism at The Vic, and in the 68th minute Davis swivelled away from his marker in the box, but just couldn’t divert his effort on target.

Back at the other end Voglsammer should have perhaps scored a second when he steered his shot wide from close range, but Flemming made sure of the points eight minutes from time when his free-kick evaded a number of bodies and nestled into the net.

Substitute Mario Gaspar headed over late on, as Bilić’s charges continued to battle for a route back into the clash, but Millwall - who had won the reverse fixture in October - held firm to maintain their clean sheet, and they could have had a third goal when Bradshaw was again denied by Bachmann at the death.