So do I have this correct, Arsenal only need 1 point total in their final 2 CL group stage matches in order to advance?
And they have Marseilles at home still to come, or is that on the road?
Arsenal is clearly in the best position in the group but will likely need to take more than 1 point to finish in the top 2 since Napoli and Dortmund could both
possibly end up on 12 points.
There's a few scenari in which 1 point would be enough for Arsenal but those are probably not the most likely.
Arsenal plays Marseille at home next and 3 points seals the deal if coupled with Napoli taking at least a point at Dortmund and, even with a Napoli loss means Arsenal only needs to not lose by 4+ goals the final matchday.
If Arsenal don't get the full 3 points against Marseilles at home next round and Dortmund beats Napoli, Arsenal would very likely have to get a result away at Napoli the final day to advance.