Chelsea made 11 changes from the team which defeated Huddersfield in the FA Cup fifth round on Saturday and, as expected, both Frank Lampard and captain John Terry were rested.
Coach Avram Grant kept faith with a 4-3-3 system which saw Didier Drogba lead the attack flanked by Florent Malouda and Joe Cole.
Olympiacos were clearly looking to contain Chelsea with a 4-5-1 formation that left Darko Kovacevic the lone striker.
Olympiacos: Nikopolidis, Zewlakow, Julio Cesar, Antzas, Pantos, Ledesma, Galletti, Torosidis, Djordjevic, Stoltidis, Kovacevic.
Subs: Sifakis, Patsatzoglou, Leonardo, Leonel Nunez, Mitroglou, Belluschi, Sisic.
Chelsea: Cech, Belletti, Carvalho, Alex, Ashley Cole, Essien, Makelele, Ballack, Malouda, Drogba, Joe Cole.
Subs: Cudicini, Lampard, Obi, Kalou, Wright-Phillips, Terry, Anelka.
Referee: Konrad Plautz (Austria)