Stephen McGinn is in contention for his first Watford appearance for 14 months.
The midfielder suffered a cruciate knee ligament injury at Doncaster in February of last year but has slowly worked his way back to fitness, culminating in a second 90-minute run-out for the club's reserves earlier this week.
Although a starting berth will be beyond McGinn, Hornets manager Sean Dyche must decide whether or not to include the Scot among his substitutes and possibly hand him a late cameo.
Otherwise, Dyche has a fully-fit squad to select from as Watford entertain a Boro side aiming to gatecrash the top six on the final day.
Adrian Mariappa returned from suspension as a substitute in last weekend's 2-2 draw at Peterborough and will again challenge Martin Taylor and Nyron Nosworthy for a start at the heart of defence.
Middlesbrough boss Tony Mowbray has no fresh injury concerns ahead of the club's play-off decider.
Full-back Justin Hoyte limped out of last Saturday's 2-1 home win over Southampton with muscle tightness, but is expected to be available for the crucial game at Vicarage Road.
Striker Marvin Emnes has been playing with a niggling knee injury which has been carefully managed, but he too should be passed fit.
Only skipper Matthew Bates remains on the long-term casualty list as he continues his recovery from the fifth cruciate ligament problem of his career.
Boro must win at Watford and hope sixth-placed Cardiff lose at Crystal Palace to leapfrog them into the play-off places, with the Bluebirds knowing even a draw should be enough to see them through because of a far superior goal difference.
