The final round of Champions Cup pool games is here for 2017/18 and this season's standings are perhaps the tightest in the history of European competition.
Just one side is assured of quarter-final progression in Leinster as we head into the last round of fixtures.
Here's who will need what to book a place in the final eight. This may get complicated...
Pool 1
Les Kiss' Ulster gave themselves a huge chance of progression after a vital victory over La Rochelle at Kingspan last week put them top of the pool.
The Irish province will know if they can travel to Wasps and pick up a victory they will be guaranteed of a quarter-final spot - though this may only be as one of the best three runners-up.
With La Rochelle set to take on an already-eliminated Harlequins at the Stade Marcel-Deflandre, a bonus-point success for the Top 14 outfit would see them finish on 21 points, placing them ahead of Ulster due to head-to-head: La Rochelle picked up a bonus-point success over Ulster in France and losing bonus-point in Belfast.
Should Ulster beat Wasps in Coventry with a bonus-point, however, they will be assured of top spot in their pool with 22 points, and this would also be enough for a home quarter-final.
There is also a scenario whereby Ulster lose but pick up a losing bonus-point, and progress with 18 points, depending on how their points difference stacks up with other potential teams on 18 points come the end of the weekend.
For Wasps, it's very difficult to get out of the pool after last week's capitulation from 21-0 ahead at Harlequins.
Dai Young's men must earn a bonus-point victory over Ulster and the Irish province must not take a losing bonus-point, while Quins must beat La Rochelle in France and the Top 14 club must not take a losing bonus-point either.
Even then, Wasps would be level with Ulster on 17 points, but would progress as pool winners due to a better head-to-head, provided they win with a bonus-point and La Rochelle take nothing at home to Quins. It's a tough ask...
Pool 2
Despite their surprise defeat at Northampton last week, Clermont are still in charge of Pool 2 and know victory over Ospreys at the Marcel Michelin on Saturday will guarantee progression, and a home quarter-final.
Indeed, a bonus-point success at home to the Ospreys could be enough for Clermont to finish the pool stages as number one seeds - if Leinster lose at Montpellier without a losing bonus-point. This would then come down to points difference, with Clermont's currently +44 and Leinster's +74.
The Ospreys kept their European campaign alive with a 15-15 draw against defending champions Saracens at the Liberty Stadium last time out, and a victory away at Clermont would see them leapfrog the French club - provided they win by more than five points (Clermont won by five at the Liberty).
If Clermont lose to the Ospreys but pick-up two bonus-points: one for scoring four tries or more and another for losing by seven or less, the Top 14 club would top the pool despite losing, with the Ospreys second. This would change if the Welsh region pick up a bonus-point success and win by more than five points.
If the Ospreys beat Clermont, Saracens are out no matter what they do. Even a bonus-point success at home to Northampton would not be enough owing to their head-to-head record with the men from the Auvergne.
Pool 3
Leinster are the only side in the competition already qualified for the knockout stage, and even a losing bonus-point at Montpellier would be enough to see them finish as number one seeds.
Montpellier's Champions Cup future suffered a big blow last weekend as they lost at Exeter, and their fate hangs very much at the feet of the Chiefs.
If Exeter win in Glasgow, Montpellier are out no matter what they achieve at home to Leinster. A bonus-point success for the Chiefs at Scotstoun would in all probability see them confirm a quarter-final spot with 19 points as one of the three best runners-up.
If Exeter lose and Montpellier pick up a bonus-point win over Leinster, 18 points could still see Vern Cotter's men through, though this is extremely unlikely due to their -24 points difference at present.
Pool 4
Munster's loss at Racing 92 last Sunday cost them a chance to qualify a week early, but any victory at home to Castres will see the Irish province progress.
Johann van Graan's side will be seeking a home quarter-final though and to achieve this, they will have to beat Castres with a bonus-point at Thomond Park- and even this might not be enough.
Leinster cannot be caught and if Clermont and Toulon are victorious, and Ulster win with a bonus-point, Munster would be away from home in the quarter-finals.
Munster fans will be hoping for a try bonus-point win, a Scarlets victory over Toulon without the Welsh side scoring four tries and then a better points difference than the West Wales region to be at home come late March/April.
If Ulster beat Wasps without a bonus-point or La Rochelle beat Harlequins with a bonus-point in Pool 1, they would be on the same points as Munster (21) and points difference would decide seedings and potential home quarter-final placings.
On the flip side, Racing's entertaining victory at the U Arena over Munster has maintained their European survival heading into the last week.
If Racing can travel to Welford Road and pick up a victory against a Leicester side already out and embarrassed at Castres last week, they should be through as one of the three best runners-up at least. If Munster lose to Castres, Racing would top the pool.
There is also an unlikely scenario where Castres could still top the pool. A bonus-point success over Munster at Thomond Park and defeat for Racing would see Castres top the standings with just 17 points.
Pool 5
The magnificent rugby on display from the Scarlets at Bath last Friday has put them in a great position in Pool 5, with three-time European champions Toulon set to visit.
A victory for Toulon at Parc y Scarlets would see them top the pool and all but guarantee a home quarter-final. A bonus-point success in west Wales would ensure a quarter-final at the Stade Mayol.
If Scarlets overcome Toulon, they will top the pool and will be in the mix for a home quarter-final depending on results and points difference elsewhere.
A losing bonus-point could be enough for Toulon to join Scarlets in the last eight.
Bath need the full five-match point haul in Italy against Benetton to throw their hat into the mix. If Toulon win and Scarlets pick up a losing bonus-point, Bath are out no matter what they do.
If Bath pick up the bonus-point win they require at Benetton, Scarlets win and Toulon do not pick up a losing bonus-point, Bath and Toulon would both finish on 18 points.
In this situation, Bath would only finish above Toulon courtesy of them losing by less points at the Stade Mayol than the French side did at The Rec - Bath lost by four points in France, while Toulon by five points in the south west.
So a single point would separate the two: therein lies the margins. And 18 points might not even be enough to make it out as a best runner-up anyway.
It's all to play for!!