Europe's Pro12 has confirmed it will add two South African teams dropped from Super Rugby and expand to a 14-team, two-continent competition from this season.
Celtic Rugby, which runs the Pro12, said the Cheetahs and Southern Kings will join straight away for the 2017-18 season starting later this year. The Pro12 is currently made up of Irish, Welsh, Scottish and Italian clubs.
The prospect of northern hemisphere clubs taking on rivals from the southern hemisphere has long been wished for by rugby fans on both sides of the equator, but conflicting seasons in the north and south have previously prevented that.
With the addition of the Bloemfontein-based Cheetahs and Port Elizabeth-based Kings, Pro12 will be rebranded as the Pro14 and change to a two-conference system, instead of a straight league table, before the knockout stages.
Seven teams from the new Pro14 will qualify for the Champions Cup, Europe's top rugby competition, but Celtic Rugby said "at present" the two South African teams won't be eligible for that competition even if they finish in the qualification places. That will, for the moment, avoid the possibility of a South African team becoming the "European" champion.
Pro14 CEO Martin Anayi said the arrival of the Cheetahs and Kings "marks a bold and exciting new chapter for the Pro14 as a global rugby championship."
Celtic Rugby said the inclusion of the Cheetahs and Kings was part of a "long-term" agreement between it and the South African rugby union.
The South African union was forced to cut two teams from the southern hemisphere's leading club competition after Super Rugby decided to downscale from 18 to 15 teams.
The Cheetahs and Kings were dropped as the two smallest of the six South African teams in Super Rugby.
Joining the European competition brings complications for the Cheetahs and Kings, and for South African rugby.
South Africa's main club competition, the Currie Cup, runs July-October, overlapping with the Pro14's traditional September to May season. It's unclear how the Cheetahs and Kings will compete in both during the overlap.
Also, the southern hemisphere's international Rugby Championship is in August, September and October, and the South Africa team tours Europe at the end of every year, also possibly clashing with the Pro14 schedule for international players with the Cheetahs and Kings.
Celtic Rugby says it will release its 2017-18 schedule next week.