In that event, the RaboDirect PRO12's challenge to keep the European title within its ranks will be up and running.
Ulster, last year's beaten finalists, start against Castres at Ravenhill where they have reeled off 11 straight Heineken wins since Stade Francais won there four seasons ago.
Ulster in Belfast may be a leading contender for the shortest of straws but Castres, fourth in the Top 14 last season, have found a shorter one in Munster, having lost there on all five European visits.
Ospreys, reigning PRO12 champions and the only club to have won the Celtic League four times, open against familiar opponents in Treviso.
The most successful of the four Welsh regions will at least know what to expect, the memory of a 12-6 defeat in Italy on the opening day of the season all too fresh in the mind.
The six-match pool stage provides precious little room for error in the frenzied quest to reach the last eight.
Ulster will bank on the Ravenhill factor if they are to finish their pool ahead of Castres, Glasgow Warriors and Northampton, the Saints driven by a serious ambition to put Europe back under English rule for the first time since Wasps won it in 2007.
Ospreys know from bitter experience that they cannot stumble at home over the first hurdle, not with Toulouse and Leicester swimming in the same pool.
If the PRO12 champions are to spearhead Welsh hopes of conquering Europe at long last, they will have to do it the hard way but then the same goes for Leicester whose Heineken visits to Swansea have almost become an annual event.
Last season RaboDirect PRO12 clubs accounted for five of the quarter-finalists - Leinster, Ulster, Edinburgh, Munster and Cardiff Blues. They then made up three-quarters of the last four with Clermont Auvergne, French semi-finalists last May, the exception.
Over the last five seasons, exactly half the semi-finalists have come from the RaboDirect. Leinster have got there four times, Munster three, Ulster, Edinburgh and the Blues once.
That compares with six from the Top 14 (Toulouse 3, Clermont, Biarritz and Perpignan once) and four from the English Premiership (Northampton, Leicester, Saracens and London Irish).
Leinster are still the team to beat, something nobody has managed since Clermont two years ago. Should the holders rediscover the game for all seasons which has already brought them successive final victories, emulating Leicester's feat at the turn of the century, nobody will be surprised if they achieve an unprecedented hat-trick.
After warming up with a satisfying PRO12 home win over Munster before almost 50,000 in Dublin last weekend, Leinster kick off at home on Saturday afternoon against English opponents making their Heineken debut.
Exeter Chiefs could hardly wish for a tougher initiation, against the double champions in Dublin where Brian O'Driscoll and company have swept all before them over the last six years with the sole exception of London Irish, 12-9 winners at the RDS three years ago.
Exeter's five-try home demolition of Harlequins last Saturday will have left nobody in any doubt about their inspiring ability to look after themselves in the highest company.
The 24-strong field features six winners who account for 13 of the 17 finals - Toulouse (1996, 2003, 2005, 2010), Leinster (2012, 2011, 2009), Munster (2008, 2006), Leicester Tigers (2002, 2001), Northampton (2000), Ulster (1999). Two more have appeared in losing finals - Cardiff (1996), Biarritz (2010, 2006).
Biarritz are one of six under starter's orders this weekend to have won the secondary European competition, the Amlin Cup.
The Basques triumphed at The Stoop last May against Toulon whose stellar cast as assembled by club owner Mourad Boudjellal makes them a serious contender for the big prize.
Out on their own in the Top 14 ahead of Toulouse and Clermont, Toulon are most definitely none the worse for having lost two Amlin finals in three seasons.
Harlequins have won the competition twice (2011, 2001), as has another of the English contingent, Sale Sharks (2005, 2002).
Clermont, undeniably the best club not to have appeared in a Heineken final, have also won the Challenge Cup twice (2007, 1999).
Cardiff Blues claimed the Amlin two years ago when they came from behind to beat Toulon in Marseilles and secure the first Welsh victory in the final of either competition.
Dublin will host this season's Heineken final for the first time in the ten seasons since Toulouse beat Perpignan in the first of three all-French affairs. Whether the next final turns out to be another RaboDirect monopoly is anyone's guess so here goes:
Pool 1:
Edinburgh, Munster, Racing Metro, Saracens. Winner: Munster.
Pool 2:
Treviso, Leicester Tigers, Ospreys, Toulouse. Winner: Toulouse.
Pool 3:
Biarritz Olympique, Connacht, Harlequins, Zebre. Winner: Harlequins.
Pool 4:
Castres, Glasgow Warriors, Northampton Saints, Ulster. Winner: Ulster.
Pool 5:
Clermont Auvergne, Exeter Chiefs, Leinster, Scarlets. Winner: Leinster.
Pool 6:
Cardiff Blues, Montpellier, Sale Sharks, Toulon. Winner: Toulon.
Best runners-up:
Two from: Biarritz, Clermont, Leicester, Northampton, Ospreys.
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