Siriki Dembele's first goal of the season earned all three points for Oxford United
Oxford United claimed a first win in 10 Championship matches with a narrow victory over 10-man Watford.
Siriki Dembele's 82nd-minute curler was enough to earn all three points for the U's, who remain four points clear of the relegation places.
Watford defender James Abankwah was dismissed with the score at 0-0 for two yellow cards within the space of 12 second-half minutes.
The defeat is a big blow to Watford's play-off hopes - they sit 10th and are now five points outside the top six while Oxford move up two places to 18th.
The visitors dominated the early stages and Giorgi Chakvetadze's free-kick was inches away from breaking the deadlock but went inches wide.
Moments later, a clever through ball from Tom Ince sent Watford skipper Moussa Sissoko in the clear but, one-on-one, Wednesday's match-winner's effort was kept out well by a sprawling Jamie Cumming in the Oxford goal.
The hosts were always a threat from set-pieces and Cameron Brannagan's corner was met by a Ben Nelson header that went over the crossbar.
Brannagan, who returned to the side following a hamstring injury, began to have more of an influence on the match and his left-footed shot was well kept out by visiting keeper Egil Selvik.
Five minutes into the second half, Dembele was presented with a glorious opportunity as he latched on to Przemyslaw Placheta's cross but, somehow, with the goal gaping, the ex-Birmingham forward fired wide.
Watford midfielder Imran Louza then swung in a dangerous corner but Chilean central defender Francisco Sierralta was unable to hit the target as the momentum swung from one way to the other.
The visitors began to knock on the door and Edo Kayembe blazed over the bar when he ought to have hit the target following good work from substitute Vakoun Bayo before Tom Dele-Bashiru struck wide from distance.
With 11 minutes to go, Abankwah was adjudged to have brought down Placheta and was awarded a second yellow card and his marching orders by referee Bobby Madley.
The hosts made the numerical advantage pay almost instantly when, latching on to a long ball, Dembele stepped inside and curled an unstoppable shot past Selvik to claim his first goal for the club since arriving from Birmingham City in the summer.
The hosts had to soak up some late pressure but managed to cling on to a crucial three points in their fight to stay in the second tier.
Oxford scored just three minutes after James Abankwah's sending-off
Oxford United boss Gary Rowett told BBC Radio Oxford:
"It was a difficult game, not only the opposition but a bit of a swirling wind.
"It helped us to press them, it helped us to stop any rhythm particularly early on but we never seemed to build any real momentum.
"I was pleased that we found a way today, I think that was the most important thing. We found a way to win the game.
"It was a great strike from Dems [Siriki Dembele]. Just before the red card [for Abankwah], I was about to take him off so what do I know? But he came up with the goods.
"I spoke to him a little bit about that recently, just adding goals, being a little bit more selfish in that final third area, so I was really pleased he did that today."
Watford boss Tom Cleverley told BBC Three Counties Radio:
"I'm getting a little bit sick of disappointment, to be honest, when I don't feel my team are playing as poorly as the results maybe show.
"Why are we not winning the games we're in full control of? Millwall, Oxford, Stoke.
"It's a conundrum I need to solve on how we turn all this control and good play into wins because no-one wants to see a team that are playing great football but not winning matches, especially at this stage of the season.
"It wasn't a pitch where you can play the football we normally do but we saw out the first 20 minutes, lively wind affecting the play, then I thought we were in absolute control.
"If I can level any criticism at the lads today, we weren't clinical enough - 16 shots and none on target in the second half and that's why ultimately we've not won the game."
