Watford hold a shock lead over Cardiff City at the midway point of the sides' Championship encounter in South Wales.
The Hornets, who have rarely ventured into their opponents' half, broke the deadlock from a corner kick on 28 minutes.
Tommy Hoban tapped home from close range, after Matej Vydra's header had been parried by David Marshall.
Don Cowie could have levelled the scores moments later, but he fired into the side netting from a narrow angle.
Cardiff could go top of the table if they claim all three points tonight.
