Two goals in either half did for the home side, the first a penalty from Peter Whittingham aftyer Jay Bothroyd was pulled back by Craig Cathcart. Then a freak goal. 17 year old Adam Matthews launched a free kick from near the halfway line and Scott Loach misjudged the flight of the ball and it cleared him and dropped into the empty net.
0 - 2 at the break and Watford were heading towards their biggest home defeat in 5 years.
Any hopes of a revival were gone when first Peter Whittingham and then Jay Bothroyd both scored insode two minutes. Watford fought back but to no avail.
The scoreline could have been worse as Michael Chopra missed two sitters. Unusual for the man who has already scored 12 goals this season.
So Cardiff go away with a first win at Vicarage Rd in nearly 40 years and Watford are left to wait two weeks before a daunting trip to Middlesbrough on October 17th.