Nicolas Pepe is expected to be fit for Arsenal’s trip to Hertfordshire on Sunday.
The Ivorian forward did not feature for the Ivory Coast during the international break, but manager Unai Emery says he is ready to play at Vicarage Road.
Rob Holding (knee) is closing in on a return, but the game could come too soon.
Hector Bellerin (knee), Kieran Tierney and Konstantinos Mavropanos (both groin) are further away, as they step up their recovery.
Reiss Nelson, 19, will be eyeing a place in the starting XI this season after Alexandre Lacazette’s ankle injury.
Arsenal: Leno, Martinez, Maitland-Niles, Mustafi, Luiz, Papastathopoulos, Chambers, Kolasinac, Xhaka, Guendouzi, Torreira, Willock, Ceballos, Pepe, Nelson, Ozil, Aubameyang, Martinelli.