Andre Brooks scored his second goal of the season at Vicarage Road
Sheffield United ended a run of three Championship games without a win by triumphing at out-of-form Watford.
Gustavo Hamer opened the scoring for the Blades before Watford's Jeremy Ngakia levelled in an entertaining first half.
Watford had chances but were punished by Andre Brooks' winner, which gets United's promotion push back on track.
Defeat was the second in succession at home for Watford, after their unbeaten run at Vicarage Road was ended by Cardiff last week.
Victory kept the Blades third, a point behind leaders Leeds after their draw at Hull, while Watford slipped to ninth following a fourth defeat in five games.
The Blades went ahead after 13 minutes through Hamer's sixth goal of the season. He was found by Callum O'Hare, before finishing well past Daniel Bachmann, who had denied Brooks moments earlier.
But their lead did not last long. Seven minutes later, Ngakia levelled with his first Watford goal in more than four years with the club, converting Ryan Andrews' cutback from the byeline.
Rocco Vata almost turned the game on its head for Watford, bursting into the area but failing to keep his shot down and find the target.
Bachmann avoided embarrassment just past the half-hour mark when O'Hare closed down his clearance, but his interception only forced the ball wide.
Eight minutes after the restart, United restored their lead as Brooks curled an excellent effort past Bachmann from the edge of the box.
Bachmann denied O'Hare to keep Watford in it at one end, before Giorgi Chakvetadze led a counter-attack and released Vata, who was denied by Blades keeper Michael Cooper.
Watford pushed on in search of a late leveller and went close through Andrews, but he shot over after Kwadwo Baah forced his way into the area.
A tough afternoon was compounded for Watford when Bachmann went down with what looked like a significant leg injury.
'We've shown our fragilities' - Cleverley
Watford boss Tom Cleverley to BBC Three Counties Radio:
"On the balance of the second half, I thought we were good value for a point - in terms of clear-cut chances I don't remember them having much.
"One team knew how to win, the other is pretty new to it. There's not much between the teams. I told the players the month of December finds teams out and it has found us out.
"It is my job to knuckle down and get this group together because we've shown our fragilities these recent weeks.
"[Not switching off from free-kicks] is a basic part of football; I was disappointed when it happened at QPR so early, we addressed it.
"To switch off [for the second goal] was really disappointing and apart from one at the end that was one of their only chances second half."
On Daniel Bachmann's injury: "We've ruled out an ankle dislocation or a ruptured Achilles tendon. Hopefully we continue to get more good news on that."
'I'm emotional after that' - Wilder
Sheffield United manager Chris Wilder speaking to BBC Radio Sheffield: "I'm quite emotional about today; it was an incredible effort by everybody.
"We are so stretched; some players shouldn't have set foot on the pitch let alone played 75 or 90 minutes. How Tom Davies has played 90 minutes I'll never know.
"We have to use this. The supporters were incredible today; they recognised the boys were running on empty. We couldn't shake things up.
"Too much is made about style and performance. You've got to want to win; they deserved that win, players and supporters."
