Koscielny is part of a much-improved defensive unit and he is happy with how the campaign is unfolding.
"When we started the season we lost a lot of games and we had to do something to change that," he told Arsenal Player. "All the players changed their mentality and we have seen that we have a good team. All of the players defend and attack and for us that is very important.
"For two months we have been strong as a team, we have done the job well and defended very well. We have the quality to do something good in the Champions League and Premier League.
"The mentality of the team has changed and we are strong. Also we have the [attacking] players who can make the difference, players like Robin, Gervinho and Theo."