This week heralds the final round of Champions League group games, with a lucrative place in the knockout stages of the competition still up for grabs for plenty of teams.
Some of Europe's biggest names will be battling to stay in the competition, while others will be trying to secure top spot and, in theory, an easier passage through the latter stages.
For those who miss out on Champions League football after Christmas, there is still the Europa League to fall back on, with third place in the group enough to see them drop into the continent's secondary competition.
Here, Sports Mole looks at the permutations for each group taking place on Tuesday.
What promised to be a thrilling group has, in fact, already been decided as far as the top two positions are concerned.
Manchester City are already guaranteed top spot in Group A courtesy of their victory over Paris Saint-Germain last time out, condemning the French giants to second place in the process.
There are still matters to be decided behind them, though; RB Leipzig know that a win will secure third spot, but any slip-up from them would open the door for Club Brugge.
The Belgian outfit would need to better Leipzig's result at home to Manchester City to leapfrog them in the group, whereas the German side simply need to match or better Brugge's result at PSG.
Liverpool have made light work of the so-called 'Group of Death', securing top spot with two games to spare and winning all five of their games so far - another victory on Tuesday would see them become the first English club to boast a 100% record in the Champions League group stage.
It is all to play for behind them, though, with just one point separating the other three teams in the group.
Of those, Porto find themselves in the strongest position, simply needing a win at home to Atletico Madrid - or to better AC Milan's result - to secure their progress.
Atletico currently sit bottom of the standings but would progress with a win as long as AC Milan drop points, while Milan will go through if they win and Porto vs. Atletico ends all square.
Everything is already decided in Group C ahead of the final matchday, with Ajax sailing through to the last 16 as group winners.
Sporting Lisbon's win over Borussia Dortmund on matchday five saw them secure second spot, with Dortmund condemned to third and a place in the Europa League.
Besiktas, meanwhile, are guaranteed to finish bottom having lost all five of their group games so far.
There is a mouth-watering, winner-takes-all encounter at the Bernabeu on matchday six, with first-placed Real Madrid taking on second-placed Inter Milan.
Both teams are already through to the last 16, but top spot in Group D is up for grabs and whoever wins will claim it, while a draw would see Madrid win the group.
Sheriff Tiraspol's memorable Champions League campaign will come to an end on Tuesday, but their European journey is guaranteed to continue after Christmas having secured third place and a spot in the Europa League last 32.
Shakhtar Donetsk, meanwhile, have been forced to settle for last place in the group having picked up only one point and scored only one goal so far.