Connacht and Leinster could be ranked as top seeds in Wednesday’s Champions Cup draw (taking place at 1pm Irish time from EPC Rugby offices in Neuchâtel, Switzerland).
Connacht, as Pro 12 champions, are already guaranteed a Tier 1 ranking, but two from Leinster, Exeter Chiefs and Toulon will join Saracens and Racing 92.
Twenty clubs from the Aviva Premiership, the Pro 12 and the Top 14 have qualified for the tournament.
The clubs will be divided into four tiers of five, and a preliminary draw will be conducted to establish each tier.
Munster cannot be drawn in a pool with another Irish province.
Ulster will be a second or third-ranked side depending on luck of the draw.
Once Tier 1 has been established, the remaining three tiers will fall into place.
Tier 2 will include the three third-ranked clubs from the leagues – Wasps, Glasgow Warriors and ASM Clermont Auvergne – as well as the second-ranked club which was not drawn into Tier 1 and the fourth-ranked club from the same league as the club which was not drawn into Tier 1.
Tier 3 will include the two clubs ranked fourth which are not in Tier 2 as well as the three fifth-ranked clubs from each league – Northampton Saints, Scarlets and Toulouse.
Tier 4 is complete and contains the sixth-ranked clubs from each league – Sale Sharks, Munster Rugby and Castres Olympique, as well as Zebre Rugby and the seventh-ranked club from the Top 14, Bordeaux-Bègles, where Ian Madigan will play his rugby next season.
When all the tiers are completed, the main draw for the five pools will be made.
During the draw some clubs may have to be placed directly into a pool to ensure only two English and French clubs in each pool.
The draw for the Challenge Cup will also take place in Neuchâtel on Wednesday.