Arsenal defender Per Mertesacker believes that his side's 2-0 victory over Borussia Dortmund was the perfect response to their disappointing loss to Manchester United last week.

The Gunners secured their place in the knockout stages of the Champions League with their win at the Emirates Stadium as strikes from Yaya Sanogo and Alexis Sanchez were enough to secure the three points.

He told Sky Sports News: "It was a solid performance, especially defensively. We didn't give them too much. We were solid at the back. We have had a few disappointing results recently. That was a mental test and we are strong enough. We can continue now.

"It's good to score an early goal but over the 90 minutes we were solid and that's the key.

"We had to [sit down and discuss recent poor defensive performances]. After Anderlecht and Manchester United, we dropped mentally a bit. We were even stronger today. We learned from disappointments in the last weeks."

Arsene Wenger's men can win Group D if they beat Galatasaray and Dortmund lose to Anderlecht in the final games of the group stage.