South Africa and Australia open this year's championship at Ellis Park in Johannesburg on Saturday, while Argentina and New Zealand clash in their round-one opener in Cordoba later in the day.
South Africa are the current world champions and Rugby Championship holders, and look the team to beat again despite a tough two-Test visit to New Zealand, including their nemesis Eden Park in Auckland, where they have not won since 1937.
The All Blacks swept their three-match July series against an under-strength France and will have eyes on regaining a title they have won for a record 20 times, boosted by facing their bitter old rivals at home.
Australia finished their British & Irish Lions series on a high with a victory in the rain in Sydney as coach Joe Schmidt continues the Wallabies' rebuild until he hands over the reins to Les Kiss in mid-2026.
Argentina, a threat to any side on their day but also prone to inconsistency, start again as underdogs but with plenty of bite.
With the new Rugby Nations Championship to start in 2026, this will be the last southern hemisphere tournament until a likely shortened version ahead of the 2027 World Cup.
Springboks coach Rassie Erasmus has used close to 50 players this year in easy wins over Italy (twice) and Georgia, but it will be a step up in quality against Australia in Tests in Johannesburg and Cape Town in the opening two rounds.
Erasmus has continued to innovate tactics and the influence of attack coach Tony Brown on their style of play has become evident. This Springboks side is vastly improved from the one that lifted the World Cup in 2019, and is arguably also superior to the winning side in 2023.
But Erasmus admits a concern as to their battle-readiness after their July canter.
"You can look at battle-readiness in two ways," he said. "We haven't lost a player to injury, which bodes well for the Rugby Championship, but none of the matches we played were close.
"We could pick from a full squad, and we weren't challenged tactically by Italy and Georgia, but those were physical matches."
New Zealand may have swept France, but the general consensus is they are still a work in progress for coach Scott Robertson after he took over from Ian Foster following the last World Cup.
They have talisman Beauden Barrett back from a hand injury and it will be interesting to see who gets the nod at No.10 with Damian McKenzie also in the mix, and ahead of the return of Richie Mo'unga next year.
"You've got an Aussie team that played some great footy at the back of their Test series (against the Lions)," Robertson said.
"You've got the South Africans. We know how strong they are and the Argentinians on their day are so creative. It's a hell of a competition, very tight and just what we need."
Schmidt is juggling several injury concerns for Australia, whose last Rugby Championship title came in 2015, but expects the key trio of loose-forward Rob Valetini, lock Will Skelton and prop Taniela Tupou to be fit for Saturday.
Flyhalf Tom Lynagh and prop Allan Alaalatoa remain longer-term casualties.
Argentina have several injury concerns too, but welcome back Juan Cruz MallÃa, Santiago Chocobares, Marcos Kremer, Bautista Delguy, Mateo Carreras and Ignacio Ruiz from the squad that lost their July series 2-0 to an under-strength England.
