The Champions League resumes this week, and on Wednesday, two up-and-coming European sides meet in the form of Dortmund and Shakhtar Donetsk.
The German side were arguably the most impressive side in Europe's elite-club competition during the group stage, having taken just one point less than PSG's tournament-leading tally of 15, and done so in a group that contained heavyweights Real Madrid, Manchester City and Ajax.
With attractive, aggressive tactics in attack and a fast-paced, swarming defense, BVB did their fans proud and captured the admiration of neutrals. And as they enter the knockout rounds, they appear to be among the favorites to reach the final in May.
Things have changed since the group stage, however, and heading into Wednesday's match there are many reasons to believe Dortmund might show a different face.
Click "begin slideshow" to read more on the factors that could see BVB meet their match on the continental stage.