A decision on rugby union's new European Cup format is likely to be delayed until next week.
Details of the tournament were expected to be confirmed on Wednesday, but some stakeholders have not signed the deal.
Sources at clubs and unions are frustrated by the delay, but there are no indications that the process will fail.
Agreement on the format, to feature teams from each Six Nations country, will end a near two-year-long dispute.
The new European Cup will run alongside a challenge cup and a developmental tournament and will be headed by a company based in Switzerland, as opposed to current organisers European Rugby Cup (ERC).
English Premiership clubs withdrew from ERC in June 2012, and have long advocated changes to the present tournament, the Heineken Cup.
As part of the new structure, unions from England, France, Scotland, Wales, Ireland and Italy will be represented on a board, while a separate executive - run by the three leagues along with an independent chairman - will be in charge of commercial affairs.
The main cup competition will involve 20 teams rather than 24, with six qualifying from the Aviva Premiership, six from the French Top 14 and seven from the Pro12.
At least one team from each of the Pro12 countries - Scotland, Wales, Ireland and Italy - will be guaranteed a place in the tournament, while the remaining spot will go to the winner of a play-off between the seventh-placed teams in England and France.
This year's Heineken Cup features seven teams from France, six from England, four from Ireland, three from Wales and two apiece from Scotland and Italy.
The issue of who will broadcast the new competitions has been a source of contention, with Sky and BT Sport signing conflicting deals. However, it is understood they will share the coverage.
Ian Ritchie, chief executive of the Rugby Football Union - the sport's governing body in England, has been instrumental in bringing the broadcasters together, and has also been a key figure in the wider negotiations.