Eddie Jones has cautioned the Six Nations against expanding the competition after revelling in a wrestle between England and Scotland played in atrocious conditions.
Tournament organisers have distanced themselves from a report stating South Africa would join a new extended format in 2024 after revealing the proposal has not been discussed.
But calls to increase the number of sides involved persist with Japan and Georgia placed alongside the Springboks in being seen as suitable additions.
England revived their title ambitions by reclaiming the Calcutta Cup in an ugly 13-6 victory that unfolded at a hostile Murrayfield and Jones believes tinkering with a winning format is ill-advised.
“It’s called the greatest rugby tournament in the world and I think it is. So why would you want to add other teams that are going to decrease the level of competition,” Jones said.
“I can only talk from experience. Super Rugby was the golden egg of rugby – brilliant, 12 teams, competitive. As soon as it had gone to 14 and 15, it had lost its allure.
“You want the best teams playing against each other. There’s something about the Six Nations – because of the history of the relationships between the nations, it makes it more outstanding.
“Someone was giving me a history lesson on Scotland and the number of different things that have happened in the rivalry with England. So there’s a lot of meaning to a lot of people for a game like this.
“The competition is much harder contested than the World Cup. It’s become a lot more physical and it’s only going to get more so.
“You don’t want this type of game every week, but southern hemisphere coaches certainly admire the Six Nations.
“From the first Six Nations I did to now, I think we’ve seen a general rise in the quality of the teams.
“Ireland, Wales, Scotland, England – they are all operating at a high level now. The gap between the teams is so small.”
Swirling wind and incessant rain brought by Storm Ciara destroyed Saturday’s clash as a spectacle and prompted questions on whether more grounds should should the Principality Stadium in fitting a roof.
But Jones, who saw replacement prop Ellis Genge pile over for the decisive try in the 70th minute, saw only positives as England relaunched their title quest six days after losing 24-17 to France in Paris.
“I loved it. Rugby is a winter sport. Until we make it a summer sport we should be playing in winter conditions,” he said.
“It was fantastic. The players have got to adapt to the conditions and find a way to win. It’s the most intriguing rugby.
“It’s a pretty simple game in those conditions. You want the opposition to have the ball.
“We got a kick in the guts against France last weekend and you have to pull yourself together.
“We probably thought we did well finishing the World Cup as finalists and weren’t right on the job.
“To come up here and do that after we got a bit of a kick in the guts against France is one of the most satisfying wins we’ve had.”