Watford have new signings Roberto Pereyra, Younes Kaboul and Daryl Janmaat available.
Boss Walter Mazzarri will not include all three players in his starting line-up and is unlikely to make many changes from the side beaten by Chelsea.
Arsenal's Mesut Ozil could start his first game of the season after being eased back to action after Euro 2016.
Per Mertesacker, Carl Jenkinson, Danny Welbeck, Alex Iwobi and Aaron Ramsey remain sidelined by injuries.
MOTD COMMENTATOR'S NOTES
Simon Brotherton: "Maybe the chants from Arsenal fans about spending some money will die down a little now that both defender Shkodran Mustafi and striker Lucas Perez are set to arrive, but it appears neither player will be involved in this weekend's fixture at Vicarage Road.