European rugby bosses are expected to announce a final agreement on the tournament to replace the Heineken Cup on Thursday.
The 20-team tournament is expected to see six Aviva Premiership teams, six clubs from France's Top 14 competition and seven of the PRO12 sides qualify.
The final place would be taken by the winner of a play-off involving clubs from several competitions, including the second-tier tournament that is to replace the Amlin Challenge Cup.
There is also to be a new third-tier competition which is expected to run in September, from which two qualifiers would then take part in the second-tier tournament, opening it up to clubs from outside the Six Nations countries such as Georgia, Russia, Spain, Romania, Portugal and Belgium.
Press Association Sport understands an agreement is very close, and once signed all parties can then chase a resolution between broadcasters BT Sport and Sky, both of whom have indicated a willingness to agree a compromise TV rights deal.
Sky Sports managing director Barney Francis said earlier this month: "We are absolutely willing to take part in conversations that lead to a solution that is in the best interests of the game and for the fans. But it will take compromise and compromise between all parties."
European Rugby Cup, the governing body of the Heineken Cup, will be wound up in the summer.