Our defense has been outstanding in the league, but shaky in the CL. That has different reasons such as different line-ups, tougher opponents, etc. The difference to last year is that we defend as a unit, much like Dortmund does. We don't press as much as them but the whole team tracks back really fast when the ball is lost. That's why Klopp accused us of copying them like the Chinese :facepalm2:.
Martinez's suspension is a major blow as he is, next to Dante, the biggest reason for our defensive stability. Luiz Gustavo has been great before his injury but still hasn't regained his form. As someone rightly pointed out our fullbacks, Lahm and Alaba, are very offensive-minded which can be exploited by a great counter-attacking team.