Arsenal defender Koscielny comfortable alongside Mertesacker
The Frenchman fees comfortable alongside the German .
"Personally, things are getting better and better with Per," he told Arsenal Player.
"He is a very experienced player, he is an international player, he knows what the very high level is about. We know that the English league is very different than the other European leagues and there is always time to adapt. Soon he will become a key player in this team."