Watford are hoping midfielder Tom Cleverley will be fit for the visit of Bristol City.
The on-loan Manchester United midfielder missed Saturday's 1-0 defeat at Barnsley with a knee injury and faces a late fitness test.
Jon Harley deputised at Oakwell and could keep his place if Cleverley is ruled out again, although recent signing Stephen McGinn is also pushing to be involved.
Another January recruit, winger Will Buckley, will be included if he shakes off a thigh strain in time.
Arsenal loanee Henri Lansbury recovered from a stomach bug to face Barnsley and will keep his place.
Striker Danny Graham is pressing to start, having been restricted to substitute appearances in the last three games.