It's been evident throughout the entire Champions League season so far, but Dortmund showed once again that the direct nature of their attack is difficult to shut down.
Regardless of which defense they've come up against, Dortmund's ability to get the ball into the box allows their dominant strikers—starting with Lewandowski—to show their dominance on the ground and create scoring opportunities.
They are not as graceful on the counter as Madrid or even Bayern Munich, but they are just as deadly.
They move the ball with precision and quickness and don't muck about in attacking midfield and waiting for the right opportunity to fall their way. Instead, they create chances and make them count.
Dortmund won't always score four goals against top clubs, but they will score plenty of goals given the direct nature of their attacking style. And so far, it would be a brave man to suggest it isn't working.