The Scot was ruled out of Saturday's 2-0 defeat at Sheffield United with a hamstring injury and will be given a late test.
Striker Nathan Ellington made his first competitive start for the Hornets in 15 months at Bramall Lane and will be hoping to get the nod again.
Fellow frontman Tommy Smith is expected to figure again despite the ongoing speculation surrounding his future.
Young forward Marvin Sordell made his debut as a second-half substitute at the weekend and should be at least on the bench again as Watford go in search of their first league win of the season.
