NFL's #1 Defense (Eagles) vs. #1 Offense (Saints) ...what's the gamebreaker?

I picked ST play, mainly because if our ST performs like they did last week, i'll be honest we are ******. I think next in line would be turnovers, but lets face it that is important against anyone. This is our first true measuring stick, we have to elimnate the mistakes in order to be takin seriously as a playoff contender.