Troy Deeney is expected to make his comeback for Watford.
Deeney missed the highly-impressive 4-1 win over Cardiff on Tuesday with an ankle injury but has reported himself fit.
However, the former Walsall man will probably have to be content with a place on the bench after strike duo Danny Graham and Marvin Sordell put three past Cardiff between them.
Full-back Lee Hodson is still ill and will miss the game as first-choice pairing Lloyd Doyley and Andrew Taylor continue.
Midfielder Stephen McGinn sustained a broken cheekbone and eye socket against QPR earlier this month and is due to sit out first-team action for at least four weeks.
Teenage midfielder Piero Mingoia is fit again after a thigh injury and could be among the substitutes while Michael Bryan has suffered a fresh ankle injury so the winger will not be involved.
Portsmouth have a unique selection headache ahead of the game.
Midfielder Michael Brown will trigger an appearance clause in his contract if he features for Pompey, meaning that his previous club Wigan would be owed more money.
With the south coast club in financial trouble, Brown will take no part as the Hornets visit Fratton Park. The same goes for Richard Hughes, who will trigger a contract extension with one more appearance on wages Pompey can not afford.
Young midfielder Tom Kilbey is also in limbo and another appearance would trigger a payment of £50,000 to Millwall.
Striker Dave Kitson will complete a one-match ban after picking up his fifth yellow card of the season in the 3-3 draw at Leeds.
Steve Cotterill is still without striker Danny Webber. The former Watford player misses the chance to face his old club as he recovers from knee ligament damage sustained in March.