With plenty to play for in round 6, here is the state of the pools going into the final weekend of group games:
POOL 1 -
A victory for Saracens over Edinburgh would see them confirmed as pool winners. Munster have to defeat Racing Metro 92 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 results elsewhere to go in their favour if they are to emerge as one of the two best runners-up.
Racing Metro are still mathematically in the equation, but they would need a bonus point win in Limerick as well a particular set of results elsewhere to secure a best runners-up spot.
POOL 2 -
It is all about the mouth-watering Leicester Tigers v Toulouse showdown at Welford Road on Sunday. A win for either of the former Heineken Cup champions would settle the pool.
Defeat for Toulouse could still see them in contention for a best runners-up place. Defeat for Leicester could leave them in contention for Amlin Challenge Cup qualification at best.
POOL 3 -
Win, lose or draw at Biarritz Olympique on Friday, Harlequins are already guaranteed a home quarter-final and vying with Clermont Auvergne and Toulon for the top ranking of the eight qualifiers.
A bonus point win would see them confirmed as number one seeds. A win for Biarritz could put them in contention both for a best runners-up place and for Amlin Challenge Cup qualification.
POOL 4 -
Already sure of a spot in the last-eight, Ulster go to Castres Olympique in search of a first Heineken Cup win on French soil. Victory could ensure a home quarter-final depending on results elsewhere, while defeat would see them on the road in the knock-out stages.
Northampton Saints travel to Glasgow Warriors in contention for a best runners-up place and for qualification for the Amlin Challenge Cup. Meanwhile, Castres would need a lot of favourable results to book a best runners-up spot, but if they defeat Ulster the Amlin Challenge Cup is on the radar.
POOL 5 -
Even a losing bonus point at the Scarlets would almost certainly guarantee Clermont Auvergne a home quarter-final at fortress Stade Marcel Michelin.
Leinster go to Exeter Chiefs chasing a best runners-up place. A win is the minimum requirement for the reigning champions, while five points will probably be needed along with favourable results elsewhere.
POOL 6 -
A losing bonus point at Montpellier will be enough to secure Toulon a home quarter-final, but a home win for Montpellier in Saturday's all-French clash will vastly change the landscape for the best runners-up places - maybe the key game of the round.
The Heineken Cup final is returning to Dublin for a third time, and the first since Ulster became the first Irish province to win the European title in 1999. This season also marks the first time the Amlin Challenge Cup final has been staged in Ireland.
There are still tickets available for the Amlin Challenge Cup final, which will be played at the home of Leinster Rugby at the RDS on Friday, May 17. Click here to buy tickets via Ticketmaster.
There are also tickets available for both the Heineken Cup and Challenge finals as part of official ERC accommodation offers for what is the biggest weekend of European club rugby. Visit ERC Rugby Travel for more.