Those teams are Manchester United, Arsenal, Barcelona, Real Madrid, Borussia Dortmund, Bayern Munich, Valencia, Malaga, Shakhtar Donetsk, AC Milan, Porto, Paris Saint-Germain and Schalke.
Here we take a look at the issues still to be resolved in three competitive groups with Chelsea badly in need of some help from Ukrainian side Shakhtar Donetsk.
Defending European champions Chelsea need a win over Danish side FC Nordsjaelland and have to hope Juventus lose against Shakhtar Donetsk if they are to progress to the Champions League knockout stages.
Chelsea are third in Group E and their head-to-head record is inferior to both teams above them. If they fail to win, the Blues will drop into the Europa League and become the first Champions League holders to fail to reach the subsequent last 16.
Celtic need to secure a better result than Benfica to overtake them and move into second place.
The Portuguese side have head-to-head superiority over Celtic and will definitely progress with a win over group winners Barcelona at the Nou Camp, or if they match the result of Celtic, who host bottom side Spartak Moscow.
Galatasaray or Cluj can still progress in second place, although the Turkish champions have the advantage going into the final game.
A win over Braga in Portugal would see them through, while Romanian side Cluj must ensure they earn a better result than Galatasaray to qualify for the last 16. Cluj take on group winners Manchester United at Old Trafford.
Wednesday's Champions League Previews