There is no word "lose" in the Leverksuen dictionary 
That is the confidence of the Leverkusen players, they are allergic to defeat, they really want to keep winning or at least a draw, that is what drives them to continue getting good results, there are no more games left and it is worrying for them that it seems like Dortmund is already over. it has been proven that they cannot be beaten and we have seen that Xabi Alonso's Leverkusen remain a solid team by never being beaten this season. What people feared Leverkusen would lose to Dortmund turned out to be overridden by them with hard work.Dortmund was unable to win in the match against Leverkusen. And by the looks of it, they are definitely starting to look like they are going to miss the chance to finish in the fourth position. They are only two points behind Leipzig. So there is definitely a chance. But if they cannot win consistently in the matches that are left in the Bundesliga, they are not going to improve and finish in the fourth position.
For them to finish on the fourth position it is also going to take Leipzig to lose. Because if Leipzig actually is able to win the rest of the matches Dortmund is not going to get ahead of them and get on the fourth position. The biggest change for Dortmund is probably the match on the 27th when they are going to actually face against Leipzig. Because that is the chance for them to get ahead of Leipzig by winning.