Full-back Kiko Femenia could be fit for Watford's home match with Newcastle in the Premier League on Saturday.
The Spaniard has endured a stop-start campaign due to a thigh injury sustained at the end of last season but featured in the win at Norwich last time out and, although he was forced off with a niggle, he has returned to training and is in contention.
Goalkeeper Daniel Bachmann is not expected to feature due to a knee injury and, while Joao Pedro has recovered from a similar issue, this game is set to come too soon for him.
Newcastle skipper Jamaal Lascelles and key midfielder Joe Willock are out of the trip to Vicarage Road.
Defender Lascelles damaged a thigh muscle in last Friday night's 1-1 draw with Leeds, while summer signing Willock suffered a freak toe injury in training, and both men are likely to be sidelined until after the forthcoming international break.
Striker Callum Wilson (thigh) also remains in the treatment room, as do keepers Martin Dubravka (foot) and Freddie Woodman (hip), defender Paul Dummett and midfielder Jonjo Shelvey (both calf).
Watford provisional squad: Foster, Elliot, Femenia, Ngakia, Troost-Ekong, Cathcart, Kabasele, Sierralta, Masina, Rose, Etebo, Gosling, Louza, Cleverley, Kucka, Tufan, Sissoko, Sema, Sarr, King, Fletcher, Dennis, Hernandez.
Newcastle provisional squad: Darlow, Gillespie, Manquillo, Krafth, Lewis, Clark, Fernandez, Schar, Hayden, Ritchie, S. Longstaff, Hendrick, Murphy, Fraser, Saint-Maximin, Almiron, Joelinton, Gayle.
