Preston and Watford both remain unbeaten in the Sky Bet Championship after a 0-0 draw at Deepdale.
The home side had the better of the first half, with Alan Browne and Ryan Ledson forcing saves from Daniel Bachmann.
Vakoun Bayo and Rey Manaj squandered huge chances for the Hertfordshire side either side of the break.
The Lancashire side have now recorded four goalless draws in their opening five league games, while their opponents have drawn all three of their away matches.