With a win against Rafael Benitez's men by a minimum of two goals, as well as a victory away to Olympique de Marseille on Matchday 6, then Dortmund would be through.
Should Dortmund win by only one goal and take three points from their final group game in Marseille, however, they could still be eliminated, if Arsenal FC win against Marseille on Tuesday, but Napoli beat the Gunners 3-1 at the Stadio San Paolo on Matchday 6.
All three teams would then, hypothetically, have twelve points, but it would be Arsenal and Napoli who would progress by virtue of their superior goal ratio of 5:5 to Dortmund’s 4:4 in games between the group's top three.
...draw with Napoli?
If Dortmund draw against Napoli and Arsenal beat Marseille at home then Jürgen Klopp's men will be eliminated. If Arsenal lose at home, and Dortmund draw, then there remains hope going into the final Matchday.
...lose to Napoli?
If Dortmund lose to Napoli and Arsenal win, then die Schwarzgelben are out.