Alex Oxlade-Chamberlain and Santos have been handed their Arsenal Champions League debut, with the likes of Robin Van Persie, Ramsey and Gibbs rested.
Marouane Chamakh, Emmanuel Frimpong and Rosicky also start in a much-changed Arsenal line-up against Olympiakos at Emirates Stadium tonight.
Song will also debut as centreback with Mertesacker due to injuries.
Arsenal team: Szczesny, Sagna, Song, Mertesacker, Santos, Frimpong, Arteta, Rosicky, Arshavin, Oxlade-Chamberlain, Chamakh.
Subs: Fabianski, Park, Van Persie, Ramsey, Jenkinson, Gibbs, Coquelin