While the likes of Bayern Munich, Manchester City, Barcelona, Liverpool and Juventus have already confirmed their spots in the round of 16 of the 2020-21 Champions League, a handful will not learn their fate until the final matchday.
Goal has rounded up what results each team needs to safely progress into the highly-anticipated knockout stages of the flagship European club competition.
Group A
Bayern Munich have already qualified for the round of 16 as winners of Group A.
Atletico Madrid and RB Salzburg are both vying for second place and will meet each other in matchday six.
Salzburg need to defeat Atletico to make it to the knockout phases, while Atletico need to just avoid defeat to make it through.
Lokomotiv Moscow are unable to qualify for the last 16, but still have a chance of qualifying for Europa League should they beat Bayern and Salzburg fail to win.
Group B
Group B will go right down to the wire. Borussia Monchengladbach must defeat or draw with Real Madrid on the final day to progress to the knockout phases, though they have already been assured a place in the Europa League.
If they lose to Real Madrid, they can only qualify for the round of 16 only if Inter draw with Shakhtar.
Shakhtar will progress to the knockouts if they win against Inter on the final matchday, while a draw will also be enough - but only if Real Madrid fail to beat Gladbach. A defeat will not see them through.
Real Madrid need only a home victory to qualify to the knockouts, while a draw will suffice should Inter defeat Shakhtar. If they lose, they will drop to the Europa League if Inter don't beat Shakhtar.
Inter need to win against Shakhtar and rely on a win or loss between Borussia Monchengladbach and Real Madrid. A draw between the two would not be enough due to the head-to-head.
Group C
Manchester City have advanced to the knockout phases as winners of Group C, with Porto finishing in second.
Olympiakos and Marseille will both battle for third place to earn a spot in the Europa League. Marseille, who face Man City, must better Olympiakos' result against Porto to keep their hopes of remaining in the competition alive.
Group D
Liverpool finished top of their group with their win over Ajax in matchday five.
Midtjylland are to finish fourth and unable to qualify for Europa League, while the fates of both Ajax and Atalanta cannot be decided until the end of matchday six.
Ajax must win against Atalanta, while a win or draw is enough for Atalanta.
Group E
Chelsea secured first place in Group E after they smashed Sevilla 4-0, with the Spanish team finishing in second.
Krasnodar have entered the Europa League after they defeated Rennes on matchday five.
Group F
Borussia Dortmund have been assured a spot in the Champions League knockouts but need to win against Zenit to finish in first place.
Lazio must not be beaten at home to Club Brugge to progress to the last 16, while Zenit St Petersburg are eliminated.
Should Club Brugge beat Lazio, they will progress to the last 16 and Lazio will drop down to the Europa League.
Group G
Barcelona and Juventus have both progressed to the knockout stages, and first and second place will be decided on the final matchday when they face off against each other.
Dynamo and Ferencvaros are unable to reach the round of 16, with both battling it out for a spot in the Europa League.
Ferencvaros need to beat Dynamo to enter the Europa League, unless the pair draw 3-3 or higher to enable them to progress based on away goals.
Group H
Group H still has a lot to play for.
Manchester United currently sit in first place, but only need a point against RB Leipzig to progress to the last 16. They will not qualify for the Champions League should they be defeated.
PSG will finish as group winners if they beat Istanbul Basaksehir at home, due to possessing the superior head-to-head against Man Utd and Leipzig.
A draw for the French giants would also be enough.
RB Leipzig need to taste victory against Man Utd to progress to the Champions League, though a draw would suffice should PSG be beaten by Istanbul Basaksehir.
If both games end in draws, meaning that all three top teams finish the group stage on an equal number of 10 points, Man Utd would be declared group winners due to the head-to-head, followed by PSG and Leipzig.
Istanbul Basaksehir have been knocked out entirely.
