The race is on for the four remaining Heineken Cup quarter-final berths. We examine exactly what is needed by each team to make the cut.
Each of the six group winners make it through plus the two best second-place finishers.
If clubs from different pools are level on points, qualification/ranking will be based on the number of tries scored in all pool matches.
If clubs are equal on points and are in the same pool, then qualification/ranking will be based on the two matches played between the clubs concerned.
Harlequins, Clermont, Ulster and Toulon have qualified for the quarter-finals but so far only Quins are guaranteed home advantage in April.
With one round to go, there are still four places to be won along with qualification for three clubs for the Amlin Challenge Cup quarter-finals.
Victory for Saracens at home to winless Edinburgh would see them confirmed as pool winners. Two bonus points or a draw would be enough to qualify.
Munster must beat Racing Metro at Thomond Park and hope that Saracens lose to Edinburgh in order to top the pool. If both Munster and Saracens win, then Munster need to win with a bonus point and hope that either Leinster and Montpellier lose and Toulouse win. The Irish clubs are currently level on points but Munster have scored one more try than Leinster.
Racing Metro are still in with a mathematical chance... but Scotland are more likely to win the World Cup than the Parisians are of making it through.
It's all down to Sunday's clash between Leicester and Toulouse at Welford Road. Whoever wins that game will qualify.
If Leicester lose, they are almost certain to be eliminated leaving them in contention for Amlin Challenge Cup qualification at best.
A losing bonus point could be enough for Toulouse provided only one of Munster, Leinster and Northampton win with a bonus point and Montpellier lose. Two bonus points or a draw would be enough to sneak through.
Harlequins are already guaranteed a home quarter-final and are vying with Clermont and Toulon for the top ranking. A bonus-point win would see them confirmed as number one seeds.
Biarritz need to win with a bonus point and hope that Munster, Leinster and Montpellier all lose.
Victory for Ulster in Castres - a first Heineken Cup win on French soil - would book a home quarter-final.
Northampton must win in Glasgow and hope that more stars that are worth counting align. They need a bucket load of tries as well as Munster, Leinster, Biarritz and Montpellier to lose.
Likewise Castres would need a lot of favourable results to book a best runners-up spot, but if they can upset Ulster, the Amlin Challenge Cup is within reach.
A losing bonus point at Scarlets would almost certainly guarantee Clermont a home play-off.
Leinster need at least a bonus-point victory at Exeter. If either Montpellier or Toulouse get two points, then the champions need to score a lot of tries to beat Munster to the final runners-up spot.
Toulon only need a losing bonus point at Montpellier to secure a home quarter-final.
A win for Montpellier spells trouble for Leinster, Munster, Northampton and Biarritz. A draw or two bonus points should be enough for Fabien GalthiÃ©'s team to qualify.