Arsenal will continue to monitor Thomas Partey, who has resumed training after a thigh problem, but Oleksandr Zinchenko is absent with a calf injury.
Reiss Nelson and Mohamed Elneny are also unavailable for the Gunners, while Emile Smith Rowe is expected to miss out because of an ongoing groin issue.
Brentford's Sergi Canos could make his first appearance of the season after overcoming a hamstring injury.
Christian Norgaard and Ethan Pinnock both remain sidelined.
CHRIS SUTTON'S PREDICTION
Brentford got off to a great start last season by beating Arsenal at home in their first game after being promoted, and there will be a cracking atmosphere there this time too.