Reading surged to the top of the Championship and gained revenge for their three-goal midweek cup defeat at the hands of Watford.
Steve Sidwell scored his first of the season in a game in which Watford enjoyed the two best chances.
The Royals had the better of the first half but it was Watford who dominated the second period, when Reading's goal came it was somewhat against the run of play.
But there was no denying the quality of the finish. Sidwell darted in to meet a cross from Nicky Shorey, beating Paul Mayo to the ball to head beyond keeper Richard Lee.
Yet Watford should have been ahead by then. Danny Webber, searching for his 10th goal of the season, was set up for what looked a certain goal two minutes before the interval.
Watford's new signing from West Brom, James Chambers, broke down the right, cut in and sent the ball beyond keeper Marcus Hahnemann.
Webber slid in but somehow managed to stop the ball just a yard from the line and was unable to put it into the empty net.
Watford were frustrated, and Hahnemann was to frustrate them again. With fifteen minutes left on the clock the Hornets once again looked certain to equalise.
Neal Ardley sent over a corner kick which Neil Cox headed into the heart of the goalmouth. Heidar Helguson climbed to nod the ball home, but Hahnemann threw himself full length to touch the ball across the goalmouth and beyond the post to safety.
High-flyingWatford continued to press for an equaliser but shots by Ashley Young, Hameur Bouazza and Gavin Mahon failed to produce the desired result.
In fact Reading could have made the points safe and spared themselves an anxious final few minutes, but Nicky Forster, with only Lee to beat, was thwarted by a fine save from the young keeper.