Groups A and F are particularly interesting, with some of European football's heavyweights, including Manchester United, Paris Saint-Germain, and AC Milan, at risk of being eliminated in the early stages of this season's competition.
Even the teams that have already qualified aren't in the clear yet, as they need to work hard to secure the top spot. Additionally, there's the consolation prize of finishing in third place and earning a spot in the Europa League in the New Year, which many clubs are eager to fight for.
Let's check out all the groups, the teams that have qualified for the next round and the teams that could miss out entirely
Group A
Already through: Bayern MunichAlready eliminated: None
MATCHDAY SIX FIXTURES
Copenhagen vs. Galatasaray (Tuesday, 8pm)
Manchester United vs. Bayern Munich (Tuesday, 8pm)
PERMUTATIONS & ANALYSIS
- Bayern Munich have already qualified for the last 16 as group winners.
- Copenhagen will qualify for the last 16 for only the second time in their history if they beat Galatasaray. A draw could also be enough if Manchester United fail to beat Bayern Munich.
- Galatasaray will qualify for the last 16 if they beat Copenhagen. Anything other than a win will see them miss out.
- Manchester United must beat Bayern Munich and hope that the other match ends as a draw to progress. If they fail to win, or if either Copenhagen or Galatasaray win their match, then Man United will be out of the Champions League, although victory would at least guarantee third place and a spot in the Europa League.
Group B
Already through: Arsenal, PSV EindhovenAlready eliminated: Lens, Sevilla
MATCHDAY SIX FIXTURES
Lens vs. Sevilla (Tuesday, 5.45pm)
PSV Eindhoven vs. Arsenal (Tuesday, 5.45pm)
PERMUTATIONS & ANALYSIS
- Arsenal have already sealed their progress as group winners.
- PSV Eindhoven have also already qualified courtesy of their superior head-to-head record over Lens.
- Lens will secure third place and drop into the Europa League if they avoid defeat to Sevilla.
- Sevilla must beat Lens if they are to climb up to third.
Group C
Already through: Real MadridAlready eliminated: Union Berlin
MATCHDAY SIX FIXTURES
Napoli vs. Braga (Tuesday, 8pm)
Union Berlin vs. Real Madrid (Tuesday, 8pm)
PERMUTATIONS & ANALYSIS
- Real Madrid have already qualified for the last 16 as group winners.
- Napoli will join them in the knockout rounds if they avoid losing by two or more goals against Braga.
- Braga therefore need to beat Napoli by two or more goals to leapfrog them into second place.
- Union Berlin cannot finish in the top two, but could still nick third place if they beat Real Madrid and Braga lose in Naples.
Group D
Already through: Real Sociedad, Inter MilanAlready eliminated: Red Bull Salzburg, Benfica
MATCHDAY SIX FIXTURES
Inter Milan vs. Real Sociedad (Tuesday, 8pm)
Red Bull Salzburg vs. Benfica (Tuesday, 8pm)
PERMUTATIONS & ANALYSIS
- Real Sociedad and Inter Milan have both qualified for the last 16.
- Real Sociedad will finish top if they avoid defeat in Milan, whereas Inter need a victory at San Siro to go through as group winners.
- Red Bull Salzburg will finish third if they avoid defeat by two or more goals to Benfica.
- Benfica must therefore beat Salzburg by two or more goals to salvage third place.
Group E
Already through: Atletico Madrid, LazioAlready eliminated: Feyenoord, Celtic
MATCHDAY SIX FIXTURES
Atletico Madrid vs. Lazio (Wednesday, 8pm)
Celtic vs. Feyenoord (Wednesday, 8pm)
PERMUTATIONS & ANALYSIS
- Atletico Madrid and Lazio have already qualified for the last 16.
- Atletico will progress as group winners if they avoid defeat in Madrid, whereas Lazio need a win to claim top spot.
- Feyenoord are guaranteed third place and will drop into the Europa League playoff round.
- Celtic will finish bottom of the group.
Group F
Already through: Borussia DortmundAlready eliminated: None
MATCHDAY SIX FIXTURES
Borussia Dortmund vs. Paris Saint-Germain (Wednesday, 8pm)
Newcastle United vs. AC Milan (Wednesday, 8pm)
PERMUTATIONS & ANALYSIS
- Borussia Dortmund have qualified for the last 16.
- Dortmund will go through as group winners if they avoid defeat at home to Paris Saint-Germain.
- PSG will progress to the last 16 and finish top of the group if they win away to Dortmund. A draw will only be enough if AC Milan avoid defeat to Newcastle, while defeat could still see them through if the group's other game ends level.
- Newcastle United will go through if they win and PSG fail to beat Dortmund. A Newcastle victory coupled with a PSG draw would see the two sides finish level on points, in which case Newcastle would progress on the head-to-head tiebreaker.
- AC Milan will only progress if they win and PSG lose. If they win and PSG draw, then PSG would finish second due to their superior head-to-head record.
- If Newcastle vs. Milan ends as a draw, Newcastle will finish third and drop into the Europa League on goal difference.
Group G
Already through: Manchester City, RB LeipzigAlready eliminated: Red Star Belgrade, Young Boys
MATCHDAY SIX FIXTURES
RB Leipzig vs. Young Boys (Wednesday, 5.45pm)
Red Star Belgrade vs. Manchester City (Wednesday, 5.45pm)
PERMUTATIONS & ANALYSIS
- Manchester City have progressed as group winners.
- RB Leipzig are assured of second place.
- Young Boys are guaranteed to finish third and drop into the Europa League playoff round.
- Red Star Belgrade will finish bottom of the group.
Group H
Already through: BarcelonaAlready eliminated: Antwerp
MATCHDAY SIX FIXTURES
Antwerp vs. Barcelona (Wednesday, 8pm)
Porto vs. Shakhtar Donetsk (Wednesday, 8pm)
PERMUTATIONS & ANALYSIS
- Barcelona have already confirmed their place in the last 16.
- Barcelona will progress as group winners unless they lose against Antwerp and Shakhtar Donetsk beat Porto, with a seven-goal swing between Barca and Shakhtar also needed.
- Porto will advance if they avoid defeat against Shakhtar, although they cannot win the group.
- Shakhtar Donetsk will progress if they beat Porto, and could still finish top of the group in the unlikely scenario of a Barcelona defeat and big goal swing too.
- Antwerp will finish bottom of the group.
