Gorkss wins it
The Latvian international brilliantly headed home Jordan Obita's corner kick five minutes into the game, and a resolute defensive display saw Nigel Adkins' side hold on for all three points.
Credit must go to Watford who showed plenty of endeavor, but squandered a number of chances in the second period - and any shots on target were superbly dealt with by Alex McCarthy.
The home side's day was summed up as debutant Alexander Merkel was dismissed late on for a two footed lunge on Nick Blackman.
Reading: McCarthy, Gunter, Pearce, Gorkss, Williams, Obita (Cummings 85), Akpan (Blackman 82), McCleary (J Taylor 87), McAnuff (C), Pogrebnyak, Le Fondre.
Booked: Le Fondre (Ungentlemanly Conduct 21), Akpan (Persistent infringement 53), McAnuff (foul 58), Blackman (foul 90)
Booked: Merkel (Foul 45), Forestieri (Diving 83)
Red Card: Merkel (Violent Conduct 90)
Attendance: 15,725 (1,636)
The Royals lined up in a 4-4-2 formation, with Jordan Obita handed a starting berth at left back - and Danny Guthrie missing out through injury. Michael Hector was named on the bench after the completion of his loan spell with Aberdeen.
And they started in ideal fashion. Less than ten minutes had past when Kaspars Gorkss latched onto Obita's corner kick with a superb flicked header, which left Hornets captain Manuel Almunia with no chance.
Obita had won the corner kick himself with a foray forward from the full back position, and it was an excellent delivery from the Academy project.
Watford's first shot came shortly afterwards, but Lewis McGugan's scuffed effort from 25 yards bobbled harmlessly wide.
Jobi McAnuff was returning from injury and facing his former club - and the Royals skipper latched onto a stray Hornets pass twenty minutes in, before driving to the edge of the area and pulling a shot inches wide of the post.
McCarthy was tested moments later, a cross from the right wing initially cleared by Gorkss - before debutant Alexander Merkel saw his shot held by the Royals stopper.
In an increasingly entertaining encounter, Pogrebnyak then nodded over the bar at the opposite end after McAnuff's free-kick was swung into the far post.
Five minutes before the break and Watford had a carbon copy chance of their own; McGugan's set piece dropping into the area dangerously, though Deeney could only bundle wide.
Danny Williams had the first attempt of the second period - Obita's half cooked corner not completely cleared, and the American international blazing over the bar from the edge of the box.
Watford responded - a ball from deep allowing Deeney to scamper into the box, only for the forward to head straight at McCarthy.
It was a lively opening after the break - Le Fondre next to be involved, firing over after controlling a Pogrebnyak knock down.
A swift break down the right then put the visitors on the back foot, before a stinging shot was brilliantly tipped over by McCarthy.
Substitute Forestieri then fired over at full stretch with McCarthy stranded, as the home side began to turn the screw.
McGugan next to be involved - dragging past the post from range after Akpan was robbed in the middle of the park. The pressure didn't stop there - Deeney another guilty party as he clipped way over the bar from Doyley's cutback.
There was another top reflex stop from McCarthy with fifteen minutes remaining, flying low to his right to palm away a stinging shot.
The injection of fresh legs gave the Royals more resolve in the final stages - Jake Taylor bounding down the wing before clipping a decent cross to the back post, which Pogrebnyak steered off target.
Frustration was building up for the Hornets - and it bubbled over as Merkel flew into a two footed lunge on substitute Nick Blackman, leaving referee Keith Stroud with no choice but to produce a straight red card.
It was the last meaningful action of the game - as Nigel Adkins' side held on for a textbook away victory at Vicarage Road.