Watford expect Samir to be fit for Roy Hodgson’s reunion with former club Crystal Palace at Vicarage Road.
Samir was forced off in the closing stages of Saturday’s 1-0 win at Aston Villa with a head injury, but boss Hodgson said there were no concussion issues and the Brazilian centre-back trained on Monday.
Joao Pedro and Juraj Kucka, who missed the Villa Park victory through injury, will both be assessed.
Conor Gallagher will return to the Palace squad for the trip.
The on-loan Chelsea midfielder was ineligible to play against parent club Chelsea on Saturday, but is available once again.
Keeper Vicente Guaita, who was substituted at half-time at the weekend, is expected to be fit, but full-back Joel Ward – who sat out against the Blues with a knock – will be missing once again, as will fellow defender Nathan Ferguson (thigh).
Watford provisional squad: Foster, Femenia, Cathcart, Samir, Kamara, Louza, Sissoko, Kayembe, Cleverley, King, Dennis, Sarr, Bachmann, Ngakia, Troost-Ekong, Kucka, Joao Pedro, Masina, Sema, Kabasele, Kalu, Hernandez.
Crystal Palace provisional squad: Guaita, Andersen, Guehi, Mitchell, Hughes, Kouyate, Schlupp, Olise, Edouard, Zaha, Butland, Clyne, Tomkins, Riedewald, Milivojevic, Eze, Mateta, Ayew, Benteke, Matthews, Adaramola, Kelly, Rak-Sakyi.
