Arsenal hope Sead Kolasinac (ankle) is fit to play while Calum Chambers (cramp) is available.
Nacho Monreal (back), Hector Bellerin and Alexandre Lacazette (both knee) are all unavailable.
Did you know?
Arsenal won their first seven PL matches against Watford but have since lost the last two.
Alex Iwobi has scored in both of his home PL appearances against Watford.
Watford could become only the third away side to win back-to-back PL matches at Emirates Stadium, after Chelsea, in November 2009, and Swansea City, in March 2016.
The Hornets have won their last two matches 1-0, with Troy Deeney hitting the winner on both occasions. The last time a team won three successive PL matches 1-0, with the same player scoring the decisive goal each time, was Liverpool and Daniel Sturridge, in September 2013.
Referee: Martin Atkinson
Assistants: Lee Betts, Constantine Hatzidakis
Fourth official: Chris Kavanagh