With five teams through on Matchday 4, we discover who else can qualify for the round of 16 and who could be out of the running on Matchday 5.
Through to round of 16 and could be confirmed as group winners on Matchday 5: Bayern, Club Brugge, Manchester City, Napoli, Real Madrid
Could go through to round of 16 on Matchday 5: Benfica, Chelsea, Dortmund, Inter, Leipzig, Liverpool, Marseille, Paris, Porto, Salzburg, Sporting CP, Tottenham
Could be eliminated from round of 16 contention on Matchday 5 but could still finish third and reach the Europa League: AC Milan, Ajax, Atlético, Barcelona, Copenhagen, Dinamo Zagreb, Eintracht Frankfurt, Juventus, Leverkusen, Maccabi Haifa, Sevilla, Shakhtar, Sporting CP
Cannot reach the Champions League round of 16 but could still finish third and reach the Europa League: Celtic, Plzen, Rangers
Could be confirmed in fourth place on Matchday 5: AC Milan, Celtic, Copenhagen, Dinamo Zagreb, Leverkusen, Plzen, Rangers, Sevilla
Napoli are through to the round of 16. They will be confirmed as group winners if they win and Liverpool do not, or if Napoli draw and Liverpool lose.
Liverpool will be through to the round of 16 if they avoid defeat.
Ajax will be unable to reach the round of 16 if they do not win. They will be confirmed in third place and reach the Europa League if they draw and Rangers lose.
Rangers are unable to reach the round of 16 but can still finish third and reach the Europa League. They will be confirmed in fourth place if they lose and Ajax do not, or if Rangers draw and Ajax win.
Club Brugge are through to the round of 16. They will be confirmed as group winners if they avoid defeat.
Porto will be through to the round of 16 if they win and Atlético do not.
Atlético will be unable to reach the round of 16, but could still finish third and reach the Europa League, if they do not win and Porto win.
Leverkusen will be confirmed in fourth place if they lose. If Porto win, or if Leverkusen draw and Porto avoid defeat, then Leverkusen will be unable to reach the round of 16 but will still be able to finish third and reach the Europa League.
Group C
Bayern are through to the round of 16. They will be confirmed as group winners if they win, or if Inter do not.
Inter will be through to the round of 16 if they win, if they draw and Barcelona do not win, or regardless if Barcelona lose.
Barcelona will be unable to reach the round of 16 if they lose, if both games are drawn, or if Inter win. Barcelona will be confirmed in third place and reach the Europa League if Inter win, or if both games are drawn.
Plzen are unable to reach the round of 16 but can still finish third and reach the Europa League. They will be confirmed in fourth place if they lose, if they draw and Barcelona avoid defeat, or regardless if Barcelona win.
Group D
Tottenham will be through to the round of 16 if they win. They will be confirmed as group winners if they win and Marseille lose.
Marseille will be through to the round of 16 if they and Tottenham both win.
Sporting will be through to the round of 16 if they win and the other game is drawn. They will be unable to reach the round of 16, but could still finish third and reach the Europa League, if they lose and Marseille win.
Frankfurt will be unable to reach the round of 16 if they lose. They will be confirmed in fourth place if they lose and Sporting win.
Group E
Chelsea will be through to the round of 16 if they win, or if they draw and AC Milan win. Chelsea will be confirmed in first place if they win and Dinamo Zagreb do not.
Salzburg will be through to the round of 16 if they win and AC Milan do not.
Milan will be unable to reach the round of 16 if they lose by three goals or more. In that event, they would only be confirmed in fourth if Chelsea lose. If AC Milan lose and Salzburg win, AC Milan would be unable to qualify for the round of 16.
Dinamo Zagreb will be unable to reach the round of 16 if they lose and Chelsea avoid defeat. In that event, they would only be confirmed in fourth if Salzburg and Chelsea draw.
Group F
Real Madrid are through to the round of 16. Madrid will be confirmed as group winners if they avoid defeat.
Leipzig will be through to the round of 16 if they win and Shakhtar lose.
Shakhtar will be unable to reach the round of 16, but could still finish third and reach the Europa League, if they lose and Leipzig win.
Celtic are unable to reach the round of 16 but will remain in contention for third place and the Europa League if they win.
Group G
Manchester City are through to the round of 16. They will be confirmed in first place if they avoid defeat.
Dortmund will be through to the round of 16 if they win, if they draw and Copenhagen do not win, or regardless if Sevilla and Copenhagen draw.
Sevilla will be unable to reach the round of 16 if they do not win, or if Dortmund avoid defeat. Sevilla will be confirmed in third place and reach the Europa League if they win and Dortmund avoid defeat. Sevilla will be confirmed in fourth place if they lose.
Copenhagen will be unable to reach the round of 16 if they do not win, or Dortmund win. Copenhagen will be confirmed in third place and reach the Europa League if they win and Dortmund also win. Copenhagen will be confirmed in fourth place if they lose.
Group H
Paris will be through to the round of 16 if they win, or if they draw and Juventus do not win.
Benfica will be through to the round of 16 if they win, or if they draw and Maccabi do not win.
Juventus will be unable to reach the round of 16, but could still finish third and reach the Europa League, if they do not win.
Maccabi Haifa will be unable to reach the round of 16, but could still finish third and reach the Europa League, if they do not win.