Matej Vydra's fine finish has given Watford a 1-0 advantage going into the break against Leeds United.
The hosts edged a slow start at Elland Road and came close to taking the lead after David Norris's effort from deep inside the penalty hit the post.
Watford took the lead through Vydra after 28 minutes when he fired the ball into the top corner of the net from the edge of the penalty area.
Things got worse for the hosts after they had Jason Pearce sent off in the final few minutes of the half for a foul on Vydra.
