Watford can welcome back Danny Rose for the visit of Southampton.
Rose has recovered from the minor calf injury that saw him miss the trip to Everton, but fellow full-back Kiko Femenia remains a doubt with a hip problem.
The Hornets will be without forward Emmanuel Dennis, who is suspended after picking up five yellow cards.
Southampton will be without Armando Broja due to an ankle issue.
James Ward-Prowse returns from a three-game suspension while Mohamed Elyounoussi is set to recover from minor hand surgery in time.
Boss Ralph Hasenhuttl said a number of players who played in the Carabao Cup defeat at Chelsea in midweek picked up knocks and will be assessed.
Watford provisional squad: Foster, Bachmann, Elliot, Ngakia, Troost-Ekong, Cathcart, Masina, Rose, Gosling, Louza, Cleverley, Kucka, Tufan, Sissoko, Sema, Sarr, Pedro, King, Fletcher, Hernandez.
Southampton provisional squad: Forster, Lyanco, Perraud, Salisu, Valery, Armstrong, Redmond, Djenepo, Tella, Diallo, Ward-Prowse, Long, Lewis, Livramento, Walker-Peters, Bednarek, Romeu, Walcott, Elyounoussi, Adams.