Holders Saracens will play Munster, Racing 92 and the Ospreys in the 2019-20 Champions Cup after the pool stage draw was made on Wednesday.
The Gallagher Premiership champions are looking to defend the title that they have won in three of the previous four years, but face a tough group alongside Irish club Munster, who they beat in the semifinals last campaign, and French side Racing 92, who reached the quarterfinals.
Last season's runners-up Leinster will face Lyon, Northampton Saints, and Benetton while fellow top seeds Toulouse will play Gloucester, Connacht and Montpellier.
Exeter Chiefs have been drawn alongside Sale Sharks, La Rochelle and Glasgow Warriors, which will see new Chiefs signing Stuart Hogg return to face his former team.
Elsewhere, Bath and Harlequins will meet Ulster and Clermont Auvergne.
This season's final will be held at the Stade Vélodrome in Marseille, France. Saracens won last season's Champions Cup final at St.James' Park, Newcastle, where they beat Leinster 20-10 for their third Champions Cup trophy.
The Champions Cup pool stage will take place later than usual due to the Rugby World Cup, with the first games scheduled for just two weeks after the final in Japan on the weekend of Nov. 15.
This season marks the 25th year of the European competition, and the sixth of its current Champions Cup format. The final will be held on May 23, 2020.
Meanwhile in the Challenge Cup, Cardiff Blues and Leicester Tigers will face each other in a repeat of the 2009 European Cup semifinal, with the draw also being held on Wednesday.
Champions Cup Pool Draw
Pool 1: Leinster Rugby, Lyon, Northampton Saints, Benetton Rugby
Pool 2: Exeter Chiefs, Glasgow Warriors, La Rochelle, Sale Sharks
Pool 3: ASM Clermont Auvergne, Ulster Rugby, Harlequins, Bath Rugby
Pool 4: Saracens, Munster Rugby, Racing 92, Ospreys
Pool 5: Toulouse, Gloucester Rugby, Connacht Rugby, Montpellier
Challenge Cup Pool Draw
Pool 1: Castres Olympique, Worcester Warriors, Dragons, Enisei-STM
Pool 2: Scarlets, RC Toulon, London Irish, Bayonne
Pool 3: Wasps, Edinburgh Rugby, Bordeaux-Begles, Agen
Pool 4: Stade Francais Paris, Bristol Bears, Zebre Rugby Club, Brive
Pool 5: Cardiff Blues, Leicester Tigers, Pau, Rugby Calvisano