Sheffield Wednesday found Watford keeper Ben Hamer in excellent form as the play-off chasing Hornets held on for a point at Hillsborough.
Ike Ugbo, making his first start for the Owls, and Watford's Matheus Martins both hit the post, while the latter also missed the best chance of the first half when he shot wide with the goal gaping.
A point was little use to either side, with Danny Rohl's Wednesday knowing victory would put them within catching distance of Saturday's opponents Huddersfield in the relegation scrap, while Watford would have moved within a point of sixth-placed Coventry.
Wednesday were the better of the two teams in the second half, with midfielder Barry Bannan running the show, but the 36-year-old Hamer produced a series of fine stops to keep them out.
Watford are now five unbeaten in the league, but with only one of those games ending in a win, they are struggling to close the gap to the play-off places.
They had their opportunities on a weather-ravaged Hillsborough pitch as Martins' free-kick took a deflection that wrong-footed Wednesday keeper James Beadle.
The same player was handed an opportunity by Vakoun Bayo, who opted to pass rather than shoot when through on goal, but Martins had to stretch for the ball and screwed his shot wide.
Wednesday gradually got on top in the opening 45 minutes as Bannan tested Hamer from distance and then Ugbo, on loan from French side Troyes, almost notched his first goal for the club in added time.
His shot hit an upright and rebounded for Anthony Musaba, but Hamer gave a preview of what was in store in the second half by superbly keeping out his header.
The Owls turned the screw after the break, with Hamer racing off his line to deny Djeidi Gassama after Bannan had somehow squeezed a pass through to the winger.
Watford retained a threat as Ismael Kone went close and then Yaser Asprilla forced Beadle to save with his feet.
But Wednesday pressed hard as the clock ticked down and when Bannan's free kick picked out Di'Shon Bernard, it seemed his header had found a way past Hamer.
To the frustration of the home supporters, referee Rebecca Welch's wristband, hooked up to the goalline technology system, told her the keeper had grabbed the ball before it crossed the line.
Hamer had one last save to make as the game headed into added time, brilliantly turning Musaba's rising drive over the bar to ensure his side had a share of the spoils.
Watford manager Valerien Ismael told BBC Three Counties Radio:
"The pitch was really difficult. We needed two or three touches to control the ball, and in transition we missed the final pass every time through the bumpy pitch.
"We take the point and finally have a clean sheet for the first time in 15 games or two months. It's a little step but we are still unbeaten away in the league (since November).
"The mentality was good, and the structure was good. It was not a nice game to watch but you have to take what you can get when you can play every three or four days. You have to be patient and calm and make sure you remain stable.
"We have taken a clean sheet against an opponent fighting to stay in the league, which makes it very difficult."