The sport has rarely been known for making things simple, and the structure is no exception.

The Celtic nations will compete in this new league alongside their Welsh-Scottish, Inter-Provincial and European competition commitments.

The Welsh-Scottish League retains the same format, although with one less Welsh side than last season as no club was promoted from Welsh National League Division One.

Bridgend, Caerphilly, Cardiff, Ebbw Vale, Llanelli, Neath, Newport, Pontypridd and Swansea will compete alongside Scottish super-districts Glasgow and Edinburgh.

The new Celtic League also includes the Irish provinces Connacht, Leinster, Munster and Ulster.

The tournament is divided into two pools - one of eight teams and the other of seven due to the odd number of Welsh sides now in the Welsh-Scottish League.

The top four from each pool will go through to the quarter-finals in December and the final will be played on 15 December.

In order to avoid fixture congestion, Celtic League matches will also count towards the Welsh-Scottish League, while matches between the Irish sides will double as Inter-Provincial Championship fixtures.

Points at stake

But in another move to ease fixture pressure, teams will play each other either home or away in the Celtic League, with the fixture being reversed next season.

Only pool games will count towards the Welsh-Scottish League and Inter-Provincial Championship. Those in the knock-out stages will not.

The creation of the Celtic League has been dogged with problems, both practical and political, and would ideally not have its inaugural season immediately after a Lions tour.

Many of Britain and Ireland's leading players require a prolonged rest after their efforts in Australia.

It remains to be seen if Welsh and Scottish sides will field full strength teams against their Irish counterparts because the games will not count towards the Welsh-Scottish League, and vice-versa for the Irish sides where Inter-Provincial points are not at stake.

For the Welsh and Irish sides, it is the Welsh-Scottish League and Inter-Provincial Championship respectively that will still determine Heineken Cup qualification.

The Heineken Cup is once again divided into six pools of four, with the six pool winners qualifying for the play-off stage along with the top two runners up.