Munster need a victory over Quins to ensure top spot in Pool 4. Anything less and Alan Gaffney's men will be looking over their shoulders at Castres Olympique, who face a tricky trip to Wales to play the Neath-Swansea Ospreys.
For the record, Irish sides have won 26 games and lost 23 against English opposition in the Heineken Cup, although the Zurich Premiership sides can boast five Cup titles, as opposed to Ireland's sole victory (Ulster 1999).
With Biarritz Olympique, Toulouse, Stade Francais, Perpignan and Castres Olympique all chasing quarter-final spots, France's proud play-off record in the Heineken Cup looks set to continue.
Since quarter-finals were introduced to the competition in 1996-97, France has been represented by at least three clubs in the final eight. They had four out of eight in 1998-99 and have supplied three of the past four finalists (Perpignan and Toulouse in 2002-03 and Toulouse again last season). France can boast three Cup winners (Toulouse 95-96, 02-03; Brive 96-97) and five losing finalists.
The 64 quarter-finalists so far - in 1995 / 1996 the semi-finals were the first knock-out stage - have come from:
Making the final eight in the Heineken Cup is only half the job, if past tournaments are anything to go by.
The likes of Leinster are guaranteed a play-off spot, but will be going all out to secure one of the four home quarter-finals. Of the past 32 quarter-finals, only seven have been won by the away side. Munster are the only side to win two away quarter-finals.
Leinster are on target to become only the fourth team in Heineken Cup history to win all six Pool matches. They need to beat Benetton Treviso at Lansdowne Road to complete the feat.
It would be the second time in three seasons that Leinster have gone through unbeaten (the other was in 02-03), while London Wasps (97-98) and Bath Rugby (01-02) have also achieved the feat, while Leicester Tigers (five wins and a draw) were undefeated in the 2002-03 Pool rounds. Perhaps worryingly for Leinster fans, none of those teams went on to make the final, let alone win the title.