South Africa turned on the power in the second half to beat Argentina at Twickenham on Saturday and win the Rugby Championship for the sixth time, on points difference.
New Zealand's 28-14 bonus-point win over Australia in Perth earlier meant that South African needed a bonus-point victory to win the title with clear water, though their overwhelming points advantage meant that any win would be enough.
After an error-strewn first half they trailed 13-10 but two tries by Malcolm Marx and a second for Cobus Reinach were a fair reflection of a dominant second half, with Delguy’s interception second and Rodrigo Isgro's score at the death merely denying the Springboks a bonus point.
South Africa, who won the Rugby Championship title two years in a row for the first time, finished on 19 points, with New Zealand second, also on 19.
Australia ended on 11 points and Argentina 10.
"It's unreal, we spoke about it (lifting the trophy) the whole week," man-of-the-match Reinach said.
"We had not won it back-to-back before. We still have a lot of improvements to make, but we are getting there
"We knew we would not just run out here and roll over them. It takes teams 60 or 70 minutes (to break the opposition down) and Argentina are unreal.
"They have a lot of dog in them, they keep fighting all game."
The match at Twickenham was officially a home game for Argentina, and what they lost in support they will gain in finance via their share of the 70,300 crowd gate receipts.
They took an early 7-0 lead via a brilliant finish by winger Bautista Delguy and though South Africa had much possession and a dominant scrum, they made a series of handling errors.
That kept them 13-3 down late in the first half after two penalties by Santiago Carreras, switched from fly-half to full-back after last week's pummelling in Durban.
The Springboks' dominant scrum, however, eventually paid dividends, earning a series of penalties on the Argentina line before scrum-half Reinach found a gap to reduce the deficit to 13-10 at the break.
A week ago South Africa led the Pumas 25-23 at halftime but poured on the power to win 67-30 and for a while it looked as if a repeat might be on the cards.
Argentina prop Mayco Visas was yellow-carded for a high hit after 43 minutes and the South African pack took immediate advantage to bundle Marx over.
A relentless series of attacks again made space for Reinach to slip through for his second and another forward drive ended with Marx claiming a second as South Africa seemed to have taken total control at 29-13.
Delguy snatched an interception try after 65 minutes but when Carreras struck the post with a penalty three minutes from time, the destination of the trophy was assured.
Argentina replacement Rodrigo Isgro had the last word when he caught a lovely wide kick by Carreras to score in the corner but the vast majority of the crowd in green were celebrating as Carreras’s conversion sailed between the posts.
