Tito Vilanova's side will be without Carles Puyol, out with a knee injury, while Gerard Pique has a sprained ankle.
Such a prospect does not in any way concern Song.
"Clearly, with Puyol and Pique we are stronger but I am ready and I've played against Cristiano in the Premier League.
"I have not just started playing today. I've played over 200 games at Arsenal and I have nothing to be worried about.
"I am not just thinking about stopping Cristiano. What is important is to play and do the job. That is why I have come."