Watford boss Walter Mazzarri says his team could be without two key players for the clash with Sunderland on Saturday.
Captain and talisman Troy Deeney has been suffering with illness while Austrian centre-half Sebastian Prodl is struggling with a calf problem.
Odion Ighalo's departure for China in January has left the goal scoring burden for the Hornets on Deeney's shoulders, and they are light on back-up options.
January signing M'baye Niang could play through the middle but is more effective out wide, with Stefano Okaka likely to replace Deeney should he miss out.
He scored an impressive brace at Goodison Park in December but has only one other goal this season.
Prodl has been a regular alongside Younes Kaboul this season and many fan's player of the season, but Mazzarri has one eye on a busy upcoming fixture schedule, much like David Moyes with Lee Cattermole and Victor Anichebe.
He said: "Deeney has had a gastro intestine problem,
"He couldn't train last week and he needs to get in the full condition.
"I am thinking that there are three games in one week,
“If we ask all the players, they will always reply yes [we are fit to play] but then it's up to the manager to evaluate. We will evaluate Deeney. I need to see.
“If he doesn't start tomorrow, he will be ready to come from the bench. It's the same for Prödl. He came from the national team and he will be evaluated. We want him ready for Tuesday but I will sit with the doctor after training and decide.”
Christian Kabasele, Ben Watson, Valon Behrami, Mauro Zarate and Roberto Pereyra are also unavailable for the hosts.
They have been bouyed, however, by the news that Tom Cleverley has converted his loan stay into a permanent one, signing a five-year deal on Friday.