Huddersfield Town lead Watford 1-0 at half-time in the Championship thanks to an Oliver Norwood strike.
Simon Grayson's side applied early pressure through Jermaine Beckford, whose left-footed shot from the edge of the box drifted wide of the mark.
Both Troy Deeney and Marco Cassetti had chances at the other end, neither of whom managed to hit the target despite good build-up play.
The hosts took the lead on 25 minutes when Norwood found the back of the net with a free kick after Almen Abdi was adjudged to have fouled Beckford.
Norwood's strike is the difference between the two sides at the break, giving Huddersfield a strong chance of maintaining their position at the top of the league come full-time.