Rankings are based on European performance over the past four seasons in the Heineken Cup and knockout stages of the Amlin Challenge Cup.
The 20 teams who have qualified for the 2013/14 competition were graded drawn into five pools and each pool will contain four clubs. Each pool will include one club from each of the four tiers and no two clubs from the same country will be drawn in the same pool with the exceptions of France as there are seven French clubs, and England, as there are six English clubs in next season's tournament.
POOL 1: Biarritz Olympique PB, Sale Sharks, Worcester Warriors, Oyonnax
POOL 2: Bath Rugby, Newport Gwent Dragons, Bordeaux-Begles, Mogliano Rugby
POOL 3: Brive, Newcastle Falcons, Cammi Rugby Calvisano, Bucharest Wolves
POOL 4: London Wasps, Rugby Viadana, Bayonne, Grenoble
POOL 5: Stade Francis Paris, London Irish, I Caveleri Prato, Olympus Rugby XV