The Rugby Championship is set for its first shake-up since Argentina joined the competition in 2012, as SANZAAR ponder a tournament model which would mirror the Six Nations.

The tournament's current form pits Australia, New Zealand, South Africa and Argentina against each other in a home and away format but as World Rugby push on with their 'League of Nations' concept, the Herald understands the addition of two more countries has been tabled.

Israel Folau and the Wallabies could be playing in Japan more often. Credit:Stuart Walmsley

It's understood Fiji and Japan are the leading contenders to join the competition, which would then change shape.

Each of the six competing nations would clash once - mirroring the Six Nations - with the inbound July Tests and usual Spring Tours completing the 11 Test season prior to the League of Nations finals in November.