Watford forward Kwadwo Baah will be out of action until "early in the new year" after suffering a hamstring injury during the 3-2 win at Derby County on Saturday.
Baah went off after 35 minutes at Pride Park and a club statement said he had "damaged his left hamstring, although the problem is not as bad as first feared".
Goalkeeper Egil Selvik, meanwhile, will be out for "at least the next few weeks" because of a shoulder problem.
The Norwegian was ruled out of Tuesday's home game against Preston and has not played since the 1-1 draw with Bristol City on 7 November.