New Watford boss Quique Sanchez Flores will be without defender Craig Cathcart for the first game of his second spell in charge against Arsenal on Sunday.
Cathcart sustained a tear in his thigh over the international break while playing for Northern Ireland and is expected to be out for two to three weeks.
The Hornets are also without club captain Troy Deeney after he underwent knee surgery in August.
Nicolas Pepe is expected to be fit for Arsenal's short trip to Hertfordshire.
The forward did not feature for the Ivory Coast in the international break but head coach Unai Emery said he is ready to play at Vicarage Road.
Rob Holding (knee) is closing in on a return but the game could come too soon, while Hector Bellerin (knee), Kieran Tierney and Konstantinos Mavropanos (both groin) are further away as they step up their recovery.
Watford provisional squad: Foster, Gomes, Dawson, Kabasele, Janmaat, Holebas, Doucoure, Chalobah, Cleverley, Femenia, Hughes, Success, Pereyra, Gray, Deulofeu, Welbeck, Masina, Sarr
Arsenal provisional squad: Leno, Martinez, Maitland-Niles, Mustafi, Luiz, Papastathopoulos, Chambers, Kolasinac, Xhaka, Guendouzi, Torreira, Willock, Ceballos, Pepe, Nelson, Ozil, Aubameyang, Lacazette, Martinelli.