Alex Song says Arsenal's midfield is key to their success in Europe this season.

Song believes much of that success is down to the link-up play with the midfield.

"We have more people behind the attack now," he said. "When we have the ball, we can go forward and help create things, but I think we now have a midfield which can switch over quickly when we lose the ball and look quite solid.

"It is important for the midfield to have that good balance, and I think this shape has started well for us. We are enjoying playing this way.

"We started playing very well and just need to keep working on the way we are set up in training."