Rotherham were defeated by Coventry City last time out as they went down 3-1 to their fellow strugglers.
Vladimir Ivic will be hoping his side can return to winning ways on Tuesday having only won once in their last five games.
Watford have also failed to score in three of their last four league matches, and six times overall in this Championship campaign.
One man who could have a positive impact on that statistic is striker Andre Gray, who has been directly involved in three goals in four Championship appearances against Rotherham.
Ivic's men sit seven points adrift of the league leaders and will be keen to find form sooner rather than later for fear of losing ground on the promotion places.
Paul Warne will have been disappointed with his side's performance on the weekend after they found themselves 2-0 after 12 minutes against Coventry City, with only a late consolation to show for their efforts.
Rotherham have won just one of their last eight league games, and just one of their 10 away league games against Watford, which does not bode well for Tuesday night's contest.
That win came in 2002, as they secured a 2-1 victory, with a certain Paul Warne substituted on for the Millers when they were trailing 1-0.
Rotherham hover precariously above the relegation zone with only two points separating them from the bottom three, as well as lying eight points adrift of the top half.
Watford Championship form: WDDWDL
Rotherham United Championship form: LWLLDL
Ivic switched to a 3-4-3 formation midway through the second half on Saturday, and may persist with this system given the chances they created.
This would mean that Joao Pedro could be shifted wide, if Andre Gray is not declared fit.
Warne has no fresh injury concerns ahead of the game and could remain unchanged.
Watford possible starting lineup:
Foster; Ngakia, Troost-Ekong, Cathcart, Femenia; Sarr, Garner, Chalobah, Quina; Pedro, Deeney
Rotherham United possible starting lineup:
Blackman; Harding, Wood, Ihiekwe; Olosunde, Lindsay, Wiles, Barlaser, Mattock; Ladapo, Smith
We say: Watford 2-0 Rotherham United
Rotherham will not be short of effort on Tuesday night, but they will need more than that if they are to trouble Watford. We expect the Hornets to come through comfortably, in the first meeting between these two sides since 2015.