Middlesbrough duo Gary O'Neil and Julio Arca will be assessed, having missed out in midweek because of a virus.
Loan signing Jay O'Shea is in contention, but striker Scott McDonald will be sidelined for up to a fortnight with a hamstring injury.
MATCH PREVIEW
Tom Cleverley's winner gave Watford victory at Middlesbrough earlier in the season, prompting the Teesside club to part company with Gareth Southgate four days later.
It was hoped that his replacement as manager, Gordon Strachan, would lead Boro to an immediate return to the Premier League. But, with seven matches left, they are six points away from the play-off places.
Strachan has improved their home results, but their away form is a major problem. Boro have won only one of their last nine on the road and have not managed a clean sheet in 13 away matches.
They visit a Watford side that sits one place above the relegation zone, having lost six of their last seven league games. A midweek defeat against fellow strugglers Sheffield Wednesday was a major blow for Malky Mackay's men.
MATCH FACTS
Head-to-head
• A win for Watford would complete the club's second league double over Middlesbrough. The only one to date was in the 1989/90 season.
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• Middlesbrough have won on five of their 11 previous league visits to Vicarage Road.
Watford
• This is Watford's 41st league and cup fixture of the season. They have played fewer games than any other Championship team.
• Watford have won only one of their last eight matches and are bottom of the Championship's 'form table'.
• The Hornets are one of six teams in the division not to have lost a match in which they scored the opening goal this season (W10, D3).
• A win would be only their second home victory against a current top-half club.
Middlesbrough
• Tuesday's 2-0 home win against Preston is Middlesbrough's only victory in their last five matches.
• Boro have won more Championship games 2-0 (six) and lost more matches 1-0 (eight) than any other team in the division.
• Julio Arca is waiting to make his 250th league appearance, and Leroy Lita his 150th start.
MOST RECENT MEETING
Middlesbrough 0-1 Watford (17 October 2009)
Watford scorer: Cleverley 26.
Source: BBC Sport
Source: BBC Sport