The Gunners need a minor miracle to make the quarter-finals of the competition after suffering a 5-1 defeat at Bayern Munich in the first leg of their last-16 tie on Wednesday night.
Despite the seemingly impossible nature of the task, Koscielny has said that "in football, you never know", insisting that his team will fight until the very end.
"In football, you never know. We are professional, we have a second leg and we will try to win. But after a game like this it's very difficult. But we'll fight because we are professional and we play for Arsenal," Koscielny told the club's official website.
Koscielny was forced off with an injury early in the second period of the last-16 first leg, when the score was 1-1.