Fresh from their stunning RaboDirect PRO12 success against reigning European Champions Leinster, the Ospreys have been paired with continental giants Toulouse and Leicester Tigers, as well as Italian outfit Benetton Treviso in Pool 2.
Toulouse and the Tigers have won the continent's top club competition no fewer than six times, with the French side picking up the trophy in 1996, 2003, 2005 and 2010 and Leicester doing likewise in 2001 and 2002.
The Ospreys have only met Toulouse twice - back in the first season of Heineken Cup rugby in 2003/04 - and are yet to record a win against the reigning Top 14 Champions. Leicester are far more familiar foes, however, with the two teams having met six times in the pool stages in the last seven seasons and the Ospreys winning two and drawing one of the last three meetings.
The Scarlets face a similarly tough challenge as they prepare to take on reigning champions Leinster, last season's semi-finalists Clermont Auvergne and in-form English newcomers Exeter Chiefs.
Having made it through to the Amlin Challenge Cup quarter-finals earlier this year following a Heineken Cup campaign that began with a stunning victory over Northampton but stuttered with three defeats in a row in the middle rounds, the Scarlets will have to be at their very best to make it out of Pool 5.
Leinster have won three of the last four Heineken Cups, although the Ospreys showed they are beatable when they triumphed at the RDS at the end of last month. The Scarlets have come out on top on two of the five occasions they've met in Europe, but the last of those wins was 13 years ago.
New coach Simon Easterby will be hoping to avoid a repeat of the two occasions the Scarlets have met Clermont when the star-studded French side, who include Wales full back Lee Byrne among their ranks, ran out convincing winners both home and away in the 2007/08 campaign.
Exeter will be embarking on their debut Heineken Cup outing after finishing fifth in the Aviva Premiership. Rob Baxter saw his side beat the Dragons in the Amlin last time out and will no doubt be after a similar result against more Welsh opposition.
The Scarlets have a proud record in Europe, though, and can boast three semi-finals and seven Heineken Cup quarter-finals among their list of previous achievements.
As for the Blues, they have been paired with Top 14 runners up Toulon and fellow French side Montpellier, as well as former Challenge Cup winners Sale Sharks in the last of the six pools.
Phil Davies will be keen to repeat his Heineken Cup success of 2007 when he led the Scarlets to the last four and the Blues will fancy their chances of progressing to a second quarter-final in a row.
The Blues beat Toulon in the Amlin final two years ago as they became the first Welsh team to taste European glory, while Sale have been beaten twice in four attempts in this competition.
Montpellier, who qualified for the French Championship play-offs again this year having made the final in 2011, will provide new opposition for the Blues as the sides have nevr met before in a competitive fixture.
Heineken Cup pools