Watford manager Tom Cleverley has confirmed defender Kevin Keben will be sidelined for at least a further six weeks.
The Cameroon under-23 international has only made one appearance for the Hornets since making the move from Toulouse in the summer after arriving with a knee issue.
Cleverley said in his pre-match press conference, external that Keben could be out for as long as two months following surgery on another knee issue.
Pierre Dwomoh is also set to miss Friday night's Championship match at Plymouth Argyle due to illness while fellow midfielder Festy Ebosele serves a one-game suspension.