#2 Paris St. Germain
For PSG, the scenario is simple. They need to beat Red Star Belgrade to be assured of qualification for the Round of 16.
The permutations and combinations come in for the French club only if they drop points against Red Star.
If PSG draw:
A Napoli win or a draw in the other game at Anfield would see the French champions qualify for the Round of 16 as group runners-up.
If Liverpool beat Napoli, that would mean the French Champions will get dumped out of the group, on account of the tie-breaking criteria in the mini-league between them, Napoli, Liverpool.
Currently, this is how that mini-league stacks up:
If PSG lose:
A Napoli win or draw would seem them go through. But a Liverpool win by any scoreline would see the French champions having to settle for a Europa League spot.