Watford look set to be without Keinan Davis once again for the visit of Middlesbrough.
The on-loan forward has been suffering with illness and missed a number of matches, including the Hornets' defeat to QPR at the weekend.
Both Ismaila Sarr and Joao Pedro have missed matches recently with hamstring stiffness and a calf issue respectively, and although both played on Saturday, two games in a short space of time could prove too much.
Tom Cleverley (calf), Imran Louza (knee), Samuel Kalu (hamstring) and Tom Dele-Bashiru (knee) remain long-term absentees.
Middlesbrough will hope to have goalkeeper Zack Steffen available for the trip.
The Manchester City loanee missed Boro's win over Swansea on Saturday after failing a late fitness test on a knee problem.
Liam Roberts will keep his place if Steffen misses out.
Chuba Akpom and Josh Coburn are expected to remain sidelined, with no new injury concerns for manager Chris Wilder.
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