David Moyes is remaining cautious over rushing Lee Cattermole back from his long-term hip injury ahead of the Watford game.
The influential midfielder has missed most of the season but revealed yesterday he is ready to return against the Hornets when the Premier League resumes this weekend.
But Moyes remains cautious over rushing him back too soon given how long he has been out this season.
Cattermole took part in a behind-closed doors game against the Under-23 side during the international break and has been taking part in full training at the Academy of Light since the goalless draw with Burnley.
Moyes must weigh up whether to involve at Vicarage Road, with another crucial game against Leicester City next Tuesday.
Striker Victor Anichebe is also closing in on a return from a knee injury having spent time working on his rehabilitation in the US but the Watford game looks to have come too soon.
Moyes, speaking at his pre-match press conference, said: "I'm not sure Catts will be in the squad.
"He's missed the whole season and we're now in April, so we have to make sure he's right.
"Victor is getting closer. He's been in America's and now he's back he's started training. We need him and Catts."
Skipper John O'Shea needed stitches after coming off worse from a Gareth Bale tackle during the international break but will be part of the squad at Watford.
Meanwhile, Lamine Kone - who missed the Burnley draw with a twisted knee - has been training all week and is set to start.
Moyes added: "The players that were away on international duty are okay.
"John O'Shea took a fair rattle in his game but we think he's okay. Bryan Oviedo and Seb Larsson returned fine.
"Lamine Kone has trained this week. It wasn't anything too serious, Burnley just came a few days too soon.
"We go into these games knowing we have to win them because they are running out. No half measures.
"Watford are a powerful team. I think they've done fine and they have some good players in their team, so it'll be a tough game."