Domingos Quina, Troy Deeney, Nathaniel Chalobah and Joao Pedro scored for the Hornets, with Tom Barkhuizen finding the net for PNE.
Here's how the players fared on the day...
9. Scott Sinclair - 6
Playing at wing back due to the lack of full backs available and did the job well, can't fault the running but rarely a threat at the other end, the system doesn't play to his strengths though.
10. Sean Maguire - 6
Like several of his teammates he started brightly but soon drifted out of the game. Put the yards in and pulled a good cut back to Potts for his close chance but not much of a goal threat.
11. Emil Riis - 6
Willing to work hard but didn't really have much in the game. Could have arguably had a penalty in the second half of his own making, showing strength and pace against two defenders.
12. Ryan Ledson - 6
Came on for Ben Pearson but at that point the game was gone and Watford were on top. Not many chances to get his foot on the ball or have an impact.