David Ospina has replaced Petr Cech in goal for Arsenal for their Champions League tie against Olympiacos at the Emirates Stadium, while midfieder Francis Coquelin returns from injury.
Ospina also started in the Gunners last Champions League game, their 2-1 loss a Dinamo Zagreb. Olivier Giroud is suspended tonight after his red card in that game. Gabriel, however, is back after his one-game ban.
Before tonight's game, Arsenal manager Arsene Wenger said: "You have to win your home games if you want to qualify from the group stage, it is simple as that.
"We cannot afford to drop points now against anyone at home."
Wenger added: "Olympiacos dominates their league, they are a team with a big advantage - they dominate their league easily, so they can prepare for these kinds of games.
"They are well organised and have some players who know the Premier League, like (Esteban) Cambiasso and (Pajtim) Kasami who both played in England."
Arsenal: Ospina, Bellerin, Gabriel, Koscielny, Gibbs, Sanchez, Ozil, Coquelin, Cazorla, Oxlade-Chamberlain, Walcott.
Subs: Cech, Debuchy, Mertesacker, Ramsey, Monreal, Chambers, Campbell.
Olympiacos: Roberto, Elabdellaoui, Botia, Siovas, Leandro Salino, Pardo, Kasami, Cambiasso, Seba, Fortounis, Ideye.
Subs: Kapino, Finnbogason, Dominguez, Pulido, Masuaku, Vouros, Hernani.
Referee: Bas Nijhuis (Holland)
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