Gonzalo Jara Reyes should be fit for Brighton but Will Buckley misses out on a return to his former club.
Chile international Reyes suffered a knee injury during Saturday's goalless draw at Birmingham but boss Gus Poyet expects him to be available.
However, winger Buckley tweaked a hamstring during the warm-up at St Andrew's and has been ruled out.
Midfielder Vicente and striker Will Hoskins are out with thigh injuries and join long-term absentees Gary Dicker (leg), Adam El-Abd (foot) and Tommy Elphick on the sidelines.
Defender Lewis Dunk is pushing to return after he was rested on Saturday and on-loan Leeds forward Billy Paynter could start after impressing on his debut as a substitute.
Watford hope to receive a boost as they assess a key quartet.
Skipper John Eustace (back) and defender Lloyd Doyley (thigh) stand an outside chance of featuring at Vicarage Road having missed Saturday's thrilling 3-2 victory over Peterborough, a win which ended a run of four successive defeats.
On-loan pair Michael Kightly and Craig Beattie, who was hoping to make his debut following his switch from Swansea, were also ruled out with hamstring injuries.
The latter pair will be monitored prior to the clash, although it is Eustace and Doyley who stand a better prospect of returning in time to face a Seagulls side who are winless in eight league matches.
Centre-back Martin Taylor continues to miss out with his collarbone complaint, as does midfielder Stephen McGinn (knee).