The Champions League is back and for some clubs it’s make-or-break time.
On matchday four, 11 sides can guarantee their places in the knockout phase of the competition while others – including Borussia Dortmund – face elimination if results go against them.
Sportsmail breaks the tournament down group by group to see how it could all work out…
Manchester United can secure a place in the Champions League knockout rounds this week
Real Madrid go to Tottenham knowing victory will guarantee their progression
But victory for Tottenham at Wembley will see Harry Kane and Co into the next round
As it stands: Manchester United (9 points), Basle (6), CSKA Moscow (3), Benfica (0)
Matches: Manchester United vs Benfica, Basle vs CSKA Moscow
There are a couple of routes through for Jose Mourinho and United when they take on the Portuguese opponents at Old Trafford.
A draw will be enough if CSKA Moscow lose at Basle, but the Red Devils can still qualify if the Russians get something in Switzerland.
Victory over Benfica, combined with a draw or Basle victory, will send United through.
If United avoid defeat and Basle beat CSKA, both teams progress. It’s looking bleak for Benfica, who need a minor miracle and really have to beat United to stand any meagre chance of staying in the competition.
Romelu Lukaku will be hoping to score the goals that send United into the last 16
As it stands: PSG (9), Bayern Munich (6), Celtic (3), Anderlecht (0)
Matches: PSG vs Anderlect, Celtic vs Bayern Munich
Like United, PSG are on a collision course with the knockout rounds.
Neymar and Co will go through if they win and Celtic fail to beat Bayern, or if they draw and Celtic lose.
Should PSG avoid defeat against lowly Anderlecht, Bayern will also progress if they beat Celtic at Parkhead.
PSG’s prolific front three can secure a last-16 spot in a couple of ways this week
As it stands: Chelsea (7), Roma (5), Atletico Madrid (2), Qarabag (1)
Matches: Roma vs Chelsea, Atletico Madrid vs Qarabag
This one isn’t so cut and dried, though the simple equation for Chelsea is win in Rome and book a knockout place.
If Roma win at Stadio Olimpico, Qarabag will be eliminated with defeat at Atletico.
Chelsea will go through if they beat Roma in Italy on Tuesday night
As it stands: Barcelona (9), Juventus (6), Sporting (3), Olympiakos (0)
Matches: Olympiakos vs Barcelona, Sporting vs Juventus
The two favourites for qualification can both secure safe passage into the last 16 this week.
Should Barcelona avoid a surprise defeat in Greece and Juventus win in Portugal, that would be this group wrapped up with two games to spare.
Barcelona go to Olympiakos knowing a win will secure their safe passage into the next round
As it stands: Spartak Moscow (5), Liverpool (5), Sevilla (4), Maribor (1)
Matches: Liverpool vs Maribor, Sevilla vs Spartak Moscow
This one is a long way from being decided.
The only certainty that can be achieved from this set of fixtures in Maribor’s elimination.
Should the Slovenians lose at Anfield – and given they were hammered 7-0 by Liverpool at home, that seems likely – they will be knocked out if Spartak beat Sevilla.
Liverpool cannot guarantee qualification even if they beat Maribor on Wednesday night
As it stands: Manchester City (9), Shakhtar Donetsk (6), Napoli (3), Feyenoord (0)
Matches: Napoli vs Manchester City, Shakhtar Donetsk vs Feyenoord
Pep Guardiola will have a very simple message for his players in Naples: Don’t bloomin’ lose.
If Manchester City avoid defeat against a Napoli side absolutely flying in Serie A, they will navigate their way into the next stage of the competition with a couple of matches to spare.
If Feyenoord fail to beat Shakhtar in Ukraine, they are out.
Manchester City will move into the last 16 if they see off Napoli in Naples this week
As it stands: Besiktas (9), Leipzig (4), Porto (3), Monaco (1)
Matches: Besiktas vs Monaco, Porto vs Leipzig
Surprise package Besiktas have romped away at the top of the table and can progress in a couple of ways.
Number one – victory; a win over Monaco is good enough to guarantee qualification. Number the second – snatch a draw and hope Leipzig beat Porto.
Besiktas are the surprise package of Group G and have a good chance of progressing
As it stands: Real Madrid (7), Tottenham (7), Borussia Dortmund (1), APOEL Nicosia (1)
Matches: Tottenham vs Real Madrid, Borussia Dortmund vs APOEL Nicosia
It could be an excellent night to be a Spurs fans, and not so great if you’re of a Dortmund persuasion.
Tottenham and Real know that victory for either club in their crunch Wembley showdown will secure their place in the last 16.
Should the two teams draw on Wednesday night, either APOEL or Dortmund could be knocked out with a defeat in the group’s other game.
Spurs and Real drawing could end up eliminating Borussia Dortmund from the competition