Arsenal defender Ben White is out of their clash with Chelsea.
The Athleticsays the £50m summer signing from Brighton is feeling unwell and is therefore not available to be picked.
His absence is another blow for manager Mikel Arteta, who is already missing striker Alexandre Lacazette, Thomas Partey and defender Gabriel Magalhaes through injury.
White had made his debut in the Premier League opening night's 2-0 defeat against newly promoted Brentford.
Calum Chambers, who played at right back against Brentford, or Rob Holding could replace him in the heart of defence - but they could face a tough task, with Chelsea's £98m summer signing Romelu Lukaku set to play up front for Thomas Tuchel' side.