Doncaster striker Billy Sharp has an outside chance of returning to the squad.
Leading goalscorer Sharp has missed the last three matches due to a groin injury, but returned to full training this week and may be included in manager Sean O'Driscoll's depleted squad.
Midfielder Simon Gillett (knee) and defender Shelton Martis (ankle) could also return to the substitutes' bench following long-term injuries, but O'Driscoll is still without a long list of first-team players.
Midfielders James Coppinger (calf), Martin Woods (groin) and Ryan Mason (leg), striker James Hayter (calf) as well as defenders James Chambers (hamstring), James O'Connor (foot) and Mustapha Dumbuya (knee) all remain sidelined, but several players are close to a return to full training.
O'Driscoll's side halted a run of four straight league defeats in midweek with a 1-1 draw at Norwich, where on-loan pair Jason Euell and Frank Moussa both made their second appearances for the club.
Watford manager Malky Mackay is hopeful of having winger Will Buckley back in his squad.
Former Rochdale man Buckley has been out for around a fortnight with an ankle problem but is back in light training and could feature at the Keepmoat Stadium.
Youngster Michael Bryan has been out with an ankle injury but has also returned to training though he is not expected to feature in Yorkshire.
Teenage right-back Adam Thompson made his first start at Reading last weekend and will keep his place as Lloyd Doyley remains sidelined with the hamstring injury that has interrupted his season.
Doyley is expected to be out for at least a fortnight, while Tottenham winger Andros Townsend has returned to White Hart Lane after a month on loan.
The winger was scheduled to remain with the Championship club until the end of the season but has returned to his parent club with immediate effect.