Pierre-Emerick Aubameyang, who was left out of the north London derby on Sunday, returns for Arsenal. Bukayo Saka is out with a hamstring injury, so Nicolas Pepe starts.
It looks like Mikel Arteta has switched from 4-2-3-1 to 4-3-3 – although really, if we’re being consistent, we should call it 4-3-2-1. It’s the pentagon shape, basically, with three central midfielders, two wide forwards and a striker. Either that or Dani Ceballos is playing as the No10 in a 4-2-3-1, in which case you can ignore this waffle. Might want to ignore it anyway.
Arsenal (4-3-3) Leno; Bellerin, David Luiz, Gabriel, Tierney; Ceballos, Elneny, Xhaka; Pepe, Aubameyang, Smith Rowe.
Substitutes: Ryan, Okwonko, Lacazette, Odegaard, Holding, Cedric, Partey, Chambers, Pablo Mari, Nelson, Nketiah, Martinelli.
Olympiakos (3-4-3) Jose Sa; Sokratis, Ba, Holebas; Androutsos, M’Vila, Camara, Reabciuk; Masouras, El-Arabi, Fortounis.
Substitutes: Karargyris, Tzolakis, Bouchalakis, Vrousai, Drager, Bruma, Lala, Sourlis, Randjelovic.
Referee Carlos del Cerro Grande (Spain)