Arsenal are without Mesut Ozil at the Emirates Stadium, where Jack Wilshere is among the substitutes.
Ozil had been tipped for a return to the squad following a knee problem, while Wilshere impressed in the Europa League in midweek.
Alex Iwobi has been passed fit following an injury but Danny Welbeck, Calum Chambers and Francis Coquelin remain sidelined.
Brighton, meanwhile, are without suspended striker Tomer Hemed.
Arsenal: Cech; Holding, Mustafi, Monreal; Bellerin, Ramsey, Xhaka, Kolasinac; Iwobi, Sanchez; Lacazette.
Subs: Ospina, Mertesacker, Wilshere, Elneny, Maitland-Niles, Walcott, Giroud.
Brighton: Ryan, Bruno, Dunk, Duffy, Bong, Izquierdo, Stephens, Propper, March, Gross, Brown.
Subs: Krul, Knockaert, Murray, Goldson, Schelotto, Suttner, Molumby.