Dortmund might have a really big difficulty in retaining the second spot in the standings this season. I don't even talk about their leadership possibility because there is no way either Dortmund or the rest of the teams can catch up with Bayern Munich that easy. Dortmund have really tough opponents in top 4. Their form so far hasn't been impressive honestly.
They lost like the half of their games in the league so far. They have been competing in the Champions League as well on one hand maybe. But they should still be able to keep two tournaments balanced to have a decent season.