This weekend Heineken Cup fixtures will determine which teams make it through to the quarter finals but the qualification rules are complex and there are a number of permutations possible.

Below is the low down on each group setting out which sides are already through and those others that have a chance, pending on results this week:

Pool One

If Leinster avoid defeat in Biarritz tomorrow, then they will reach the last eight. Any slip-ups, and their French hosts will march on.

Pool Two

Both Stade Francais and Swansea, who clash in Paris tomorrow, are already through to the quarter-finals. On offer this weekend is a priceless home draw for the winners.

Pool Three

Cardiff have qualified for the knockout stages, and will secure a home if they topple Toulouse tomorrow. Second-placed Saracens could still make it as a best runner-up, but they must beat Ulster in Belfast tonight and score probably at least three tries.

Pool Four

Munster have already wrapped up the group, but need to be beat visitors Colomiers tomorrow for a home quarter-final. Rank outsiders Bath face scoring a likely minimum of ten tries against Newport, yet if they manage such a feat, then the quarter-finals might be reached.

Pool Five

If Colomiers beat Llanelli tonight, then they will progress as group winners. Depending on what happens at Stradey Park, Gloucester will move forward either as pool-toppers or a best runner-up with victory in Rome tomorrow. A Llanelli win opens the quarter-final door for them, but try-count is vital, and they have currently scored one less than Saracens.

Pool Six

Leicester are through, knowing that a home quarter-final is certain, provided they see off Welford Road visitors Glasgow tomorrow. French club Pau will challenge for a best runners-up spot by defeating Pontypridd and scoring tries in the process.

* The six pool winners and two best runners-up reach the last eight, their ranking determining a 1 versus 8, 2 versus 7, 3 versus 6 and 4 versus 5 line-up.

* If clubs in the same pool are equal on points, then ranking is determined by the two matches played between those clubs. Clubs level in different groups are separated by try-count.

Possible quarter-finals: Stade Francais v Llanelli, Leicester v Swansea, Munster v Biarritz, Cardiff v Gloucester.