Mari has a tight calf, while Tierney has muscle tightness and has been left out as a precaution by Arteta.
In their place, Ainsley Maitland-Niles starts at left-back, with David Luiz coming in at centre-back alongside Rob Holding.
Despite that defensive setback, Gabriel Magalhaes returns after a period of self-isolation and is on the bench, while Thomas Partey is back from a thigh injury and takes his place among the substitutes.
Arsenal XI: Leno, Bellerin, Holding, Luiz, Maitland-Niles, Ceballos, Xhaka, Saka, Smith-Rowe, Aubameyang, Lacazette
Subs: Gabriel, Willian, Runarsson, Cedric, Partey, Pepe, Chambers, Willock, Nketiah