Burnley forward Andre Gray begins a four-match ban imposed by the FA on Friday for homophobic comments he posted on social media in 2012.
Striker Ashley Barnes remains unavailable because of a hamstring injury.
Watford right-back Daryl Janmaat has been ruled out for up to six weeks with a shoulder injury sustained last weekend.
Fellow defenders Jose Holebas and Younes Kaboul are also doubts.
MOTD COMMENTATOR'S NOTES
Steve Wilson: "All the so-called golden football rules of seeking to maintain a stable squad and continuity in the manager's seat have been scrunched up into a ball of so much rubbish, and lobbed unceremoniously into the Vicarage Road bin by Watford's owning Pozzo family.