Rugby chiefs on Monday officially launched the Nations Championship, a global competition featuring 12 of the strongest teams that will crown a winning nation and decide the sport's dominant hemisphere.

Organisers said the new biennial tournament signalled a "watershed moment for rugby union, years in the making", and would transform the two existing international playing windows, in July and November.

The Nations Championship, which starts in July 2026, will replace ad-hoc tours and one-off Tests, giving more meaning to internationals played outside major tournaments.

The Six Nations teams will represent the northern hemisphere, and face the SANZAAR nations (South Africa, New Zealand, Australia and Argentina), plus Japan and Fiji, representing the southern hemisphere.

Each side will play six maches, taking on each of their hemisphere rivals from the opposing group before a Nations Championship Finals Weekend, to decide the tournament champion and winning hemisphere.

London will host the inaugural Finals Weekend, with three days of double-headers at Twickenham in November 2026.

The top-ranked team in the northern hemisphere group, and the top-ranked team representing the southern hemisphere will battle for the title.

Teams will also be competing to earn points for their group to decide the winning hemisphere.

Organisers said the championship would inject "jeopardy and context into every fixture".

Tom Harrison, CEO of Six Nations Rugby, said: "The Nations Championship has the power to redefine the future of rugby, and the partnership between Six Nations Rugby and SANZAAR signals a tectonic shift in the sport.

"Rugby's strongest nations have collaborated with a clear vision to grow the game, by challenging traditional ways of operating to create a tournament structure with genuine global relevance, which will unlock the true value of the sport."

Brendan Morris, CEO of SANZAAR, said the establishment of the Nations Championship was a "historic and exciiting move".

The first round of Nations Championship fixtures, on July 4, 2026, includes a series of blockbuster matches, with world champions South Africa hosting England, France travelling to New Zealand and Australia facing Ireland.

Rian Oberholzer, CEO of SA Rugby, said the championship would mean every Test counted "for more than just bragging rights and world ranking points".

New Zealand Rugby CEO Mark Robinson said the Nations Championship would bring an edge to the traditional Test windows and usher in a "new era for international rugby".

"Fans want to know who the best team is between World Cups and the Nations Championship will deliver a champion," he said.