Tier 1 - Stade Francais Paris, Perpignan, London Wasps, Toulon, Sale Sharks
Tier 2 - Newport Gwent Dragons, Brive, Newcastle Falcons, Worcester Warriors, Bayonne
Tier 3 - Petrarca Padova, Crociati Parma, Femi-CZ Rovigo, Agen, Exeter Chiefs
Tier 4 - Cavalieri Prato, Lyon, Bordeaux-Bègles, Bucharest Wolves, Club Rugby La Vila
There are 20 participating clubs from six countries - England, France, Italy, Romania, Spain and Wales - who will be drawn into five Pools of four teams each.
The 20 clubs will be divided into four tiers of five teams. The tiers are based on the ERC European Rankings system over the past four seasons in the Heineken Cup and the knock-out stages of the Amlin Challenge Cup and also on participation in the Pool stages of the Amlin Challenge Cup over the same four season period.
Each Pool will have one club from each of the four tiers and no two clubs from the same country will be drawn in the same Pool, except for the sixth, seventh and eighth clubs from France who will be drawn into Pools with another French club.
The result of the draw will be posted on warriors.co.uk and ercrugby.com on Wednesday