Koscielny was Ligue 2 Player of the Year in 2009 and earned a move to Lorient, for whom he scored his first goal in the French top-flight in a 1-1 draw at Marseille in March 2010. With L'OM back in his sights in the Champions League tonight, Koscielny cannot quite believe his meteoric rise.
"Two years ago I scored with Lorient in Marseille. Since then, so many things have happened to me," he told arenal.com.
"If someone had told me that I would now be playing for Arsenal, that I would have beaten Lionel Messi's Barcelona team and had been called up for France, I would not have believed it. It has been two crazy years.
"I often think of my unusual journey to the top level. I had some difficult moments which made me who I am now. I know where I'm coming from and what I had to do to get where I'm now.
"I had three great managers in Daniel Sanchez in Tours, Christian Gourcuff and now Arsène Wenger. They are very similar and share the same philosophy of football. Everything went so fast and I know that it could go as fast in the other way so I'm staying very humble. I respect football. If you get carried away, things will get back at you.
"We are approaching the Marseille game with a real momentum. We are starting to hate losing. We know they have some good players and we will have to be serious and play like we did at Chelsea. Its a very important game as if we win, we will have 10 points and be almost through."