Rafa Benitez’s Napoli have a daunting task against leaders Arsenal. They are separated by three points. Borussia Dortmund go to Marseille knowing that victory will guarantee them a spot in the knockout rounds.
Napoli and Dortmund both have nine points, three adrift of Arsenal, who only need a draw to be certain of going through. Napoli could draw and go through but that would need Dortmund to lose at a Marseille side who are still seeking their first points in the section.
If Dortmund crashes, Napoli will go through with a win. In the event of a three-way head-to-head on 12 points, the two qualifiers will be decided by the score lines between the three teams.
A draw is only enough for Napoli if Dortmund, who have a superior head-to-head record, lose. If Napoli lose they are out.
Dortmund are through if they win but, should they draw, they will have to hope Napoli loses to the Gunners. Dortmund can only afford to lose if Napoli are also beaten.