Watford goalkeeper Daniel Bachmann spilled Largie Ramazani's effort over the line in the fourth minute
Leeds United were gifted two goals in the opening seven minutes to claim a victory over Watford that sent them level on points with Championship leaders Sunderland.
Hornets goalkeeper Daniel Bachmann fumbled Largie Ramazani's shot from the edge of the area over the line and, just over two minutes later, the keeper parried a Willy Gnonto cross straight to Brenden Aaronson to sweep in from 12 yards out.
The away side got back into the contest in the opening moments of the second half after Kwadwo Baah wriggled free down the right and then reacted well to slot in when his low cross into the middle came back to him off Leeds defender Joe Rodon.
Watford looked for a leveller but could not force Illan Meslier into a meaningful save and Jayden Bogle hit the post for the Whites before Joel Piroe's rebound was kept out by Bachmann.
The Austrian goalkeeper also kept out substitute Dan James' effort late on, as Leeds went level on points and goal difference with the Black Cats.
But they only climb a place to second because they have won fewer games than the Wearsiders, who visit Luton on Wednesday.
Daniel Farke's Leeds side produced a super display to beat promotion-chasing Yorkshire rivals Sheffield United 2-0 on Friday and picked up where they left off at Elland Road.
Former Manchester United winger Ramazani cut in off the left wing and sent a firm shot at Bachmann from the angle of the 18-yard box. The goalkeeper seemed to misjudge the effort and was unable to stop it crossing the line despite a desperate lunge.
The keeper's evening went from bad to worse when he deflected Gnonto's right wing cross out to USA international Aaronson, who finished confidently.
Watford boss Tom Cleverley had made six changes from the side who were meekly beaten 3-0 by local rivals Luton on Saturday and his side did at least stay in the game in West Yorkshire.
Baah gave them hope straight after the break when he scored from close range after some poor defending from the home side.
Leeds were knocked by that but never really looked like throwing their lead away and but for some errant finishing from Piroe and James, would have ended the night top of the table.
They travel to Bristol City in one of the three early kick-offs on Saturday, while Watford will host Blackburn in one of the others.
Leeds boss Daniel Farke told BBC Radio Leeds:
"First of all I'm really, really happy with the three points.
"I was worried after 10 minutes when we were 2-0 up I have to say. Last Friday was more or less a magic night and everybody was praising us and then you go into the next game against a really good opponent and then easily go 2-0 up and it can lead to a situation where you do one step less and you end up dropping points.
"We missed an unbelievable amount of chances and if you don't score the third goal you still have to be awake and play without any mistakes.
"I have to pay compliments to our fans too as they were excellent and made sure we kept playing on the front foot."
Watford boss Tom Cleverley told BBC Radio 3CR:
"I thought we showed excellent character this evening. The personality we showed in possession was chalk and cheese from what you saw on Saturday.
"I thought we were unfortunate to come away with nothing.
(On Bachmann) "Just two freak mistakes that you don't normally see from Daniel. He's one of the best shotstoppers in the league and he's won us far more points that he has lost us but tonight wasn't his best evening.
"We went through a really strong fitness test with him yesterday because we didn't want a repeat of Saturday where you could see after 10 minutes he wasn't fit. The goals were nothing to do with that."
