Vermaelen has only just returned from long-term injury.
He told Chinese fans in an Arsenal Q&A: "To be honest I only trained for a short time with Per before that game because I had been injured since he came to Arsenal. For me it was a bit strange because I played alongside him for the first time straight away in a Champions League game.
"We know each other's qualities because I have seen him in games and you know where the other centre-back is going to be. I don't think it's a big problem."