Aviva Premiership champions Northampton could miss out on being a top-seeded 'tier one' side for the pool stages of the inaugural European Rugby Champions Cup draw because of the structure of the new competition.
The seven English qualifying clubs are ranked by their position in the final league table, meaning Saracens - who lost to Saints in the Premiership final - are the only side from the league guaranteed tier one status.
Toulon and Leinster are also confirmed in tier one, with a pre-draw to be carried out to decide which two of Northampton, Castres and Glasgow will join them as top seeds.
The French Top 14 teams and Irish, Welsh and Scottish sides from the RaboDirect Pro12 are ranked based on their league performances and on their qualification for the knockout phases of those respective competitions.
The pool stage for the 20-team competition, which replaces the Heineken Cup after months of negotiations, will be formed of five groups, each containing four clubs with the draw taking place in Switzerland on Tuesday.
The five group winners and three best runners-up will secure quarter-final places.
The second-tier European Challenge Cup is also to be drawn on Tuesday and will also feature five pools of four teams, with Stade Francais, Exeter and Cardiff Blues confirmed among top seeds.
European Rugby Champions Cup teams: Saracens, Toulon, Leinster, Northampton, Castres, Glasgow, Leicester, Montpellier, Munster, Harlequins, Racing Metro, Ulster, Bath, Clermont Auvergne, Ospreys, Sale Sharks, Toulouse, Scarlets, Wasps, Treviso.
European Rugby Challenge Cup teams: Stade Francais, Exeter, Cardiff Blues, Bordeaux-Begles, Gloucester, Edinburgh, Brive, London Irish, Newport Gwent Dragons, Bayonne, Newcastle, Connacht, Grenoble, London Welsh, Zebre, Oyonnax, Lyon, La Rochelle, plus two qualifiers to emerge from competition in September.