The draw, which will take place in Lausanne, Switzerland, will be live-streamed on HeinekenChampionsCup.com.
Saints will definitely be up against Ulster or Connacht and one of Racing 92 and Bordeaux-Bègles.
The Heineken Champions Cup will once again be competed for by 24 clubs with eight representatives from the Premiership, the PRO14 and the TOP 14 having secured their places.
For the purposes of the draw which will be run on the same lines as last season, the clubs will first be placed into four tiers based on their rankings, before being drawn into two pools of 12 – Pool A and Pool B.
Clubs from the same league in the same tier will not be drawn into the same pool.
The number 1 and number 2 ranked clubs from each league will be in Tier 1, the number 3 and number 4 ranked clubs will be in Tier 2, the number 5 and 6 ranked clubs will be in Tier 3, and the number 7 and number 8 ranked clubs will be Tier 4.
The Tier 1 and the Tier 4 clubs which have been drawn in the same pool, but which are not in the same league, will play one another home and away during the pool stage, as will the Tier 2 and Tier 3 clubs which have been drawn in the same pool, but which are not in the same league.
Once the draw is concluded, clubs will know their pool stage opponents and EPCR will begin work on the fixture schedule with an announcement of exact dates, venues, kick-off times and TV coverage following as soon as practicable.
The 2021/22 tournament will be played over nine weekends with four rounds of matches in the pool stage starting in December when Stade Toulousain begin the defence of their title.
The eight highest-ranked clubs from each pool will qualify for the knockout stage which will consist of a Round of 16 on a home and away basis, quarter-finals and semi-finals, with the final in Marseille on May 28, 2022.
2021/22 Heineken Champions Cup qualifiers
Gallagher Premiership: 1 Harlequins, 2 Exeter Chiefs, 3 Bristol Bears, 4 Sale Sharks, 5 Saints, 6 Leicester Tigers, 7 Bath Rugby, 8 Wasps
Guinness PRO14: 1 Leinster Rugby, 2 Munster Rugby, 3 Ulster Rugby, 4 Connacht Rugby, 5 Scarlets, 6 Ospreys, 7 Cardiff Rugby, 8 Glasgow Warriors
TOP 14: 1 Stade Toulousain, 2 Stade Rochelais, 3 Racing 92, 4 Union Bordeaux-Bègles, 5 ASM Clermont Auvergne, 6 Stade Français Paris, 7 Castres Olympique, 8 Montpellier Hérault Rugby
Pool draw tiers
Tier 1: Harlequins, Exeter Chiefs, Leinster Rugby, Munster Rugby, Stade Toulousain, Stade Rochelais
Tier 2: Bristol Bears, Sale Sharks, Ulster Rugby, Connacht Rugby, Racing 92, Union Bordeaux-Bègles
Tier 3: Saints, Leicester Tigers, Scarlets, Ospreys, ASM Clermont Auvergne, Stade Français Paris
Tier 4: Bath Rugby, Wasps, Cardiff Rugby, Glasgow Warriors, Castres Olympique, Montpellier Hérault Rugby