Chances were few and far between in the opening half at Vicarage Road as Watford and Peterborough battle in the Championship.
The visitors started the stronger and Tommy Rowe almost gave them an early lead but his header couldn't get under the crossbar.
The next 20 minutes or so lacked chances until Watford's Daniel Pudil eyed up a free kick. The Czech's set piece got over the wall and beat Robert Olejnik but could only clip the top of the woodwork.