DC) Laurent Koscielny
With Thomas Vermaelen doubtful with injury anyway, Koscielny is a practical certainty to start alongside Mertesacker. When the pair have completed the 90 minutes together, Arsenal have never lost a Premier League match.
DL) Keiran Gibbs
Nacho Monreal is injured, picking up a knock against Aston Villa on Monday evening. Gibbs came on for him that night, and will almost definitely start in his place against the Cottagers.