The pair became friends at Ligue 2 side Tours three years ago and the striker has been impressed with the the defender's improvement since they last played with each other
Arsenal new-boy Olivier Giroud says that Laurent Koscielny has become one of the best defenders in the Premier League.
The striker joined this summer from Montpellier and has been impressed with the improvement his new team-mate has made since the last time they were in the same side.
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The pair have been friends since they spent a season together at Ligue 2 side Tours during the 2008-09 season and Giroud believes Koscielny will only improve in the future.
The 25-year-old striker told the club's official website: "I'd say he's one of the best in the Premier League. I think he can continue to [get even better].
"He's very respectable and serious in his work. You can trust him, and his behaviour on the pitch is important. I like when a guy concentrates and is serious.
"He is like a leader on the pitch, by his behaviour. He is important for the national team now, and he is a very important player for Arsenal. He is a very good player and a very good guy."
Koscielny is part of the France squad who will face Finland and Belarus, but Didier Deschamps has confirmed that Giroud's muscle injury has ruled him out of Friday's opening qualifier.