The 26-year-old defender has missed one match so far this season for the Gunners, who have endured a tumultuous start to the campaign.
The 8-2 mauling at Manchester United was Arsenal’s low point but Koscielny believes the side are capable of impressing in European football’s elite competition, especially if they keep the back line tight.
“It is very important to defend together,” he said of tonight’s match against Borussia Dortmund. “We have the quality.
“We have new players who have arrived at the club, and it is important for us that they can provide some creativity technically in midfield. I think we can do something in this competition.”
Koscielny is likely to start at the heart of defence this evening alongside new signing Per Mertesacker.
The Germany international was signed on deadline day from Werder Bremen and Koscielny believes he adds another dimension to Arsenal’s defence.
“He is a very good defender with a lot of experience,” he said. “He is a German international, and is really important for us on the pitch.
“He is tall, which is good for our physical side. He will help me on the pitch with defensive corners.
“With Thomas [Vermaelen] it is very different. We must defend very well, and make a clean sheet more possible.”