South Africa survived a second-half Argentina onslaught to win 22-21 in Johannesburg on Saturday and finish Rugby Championship runners-up behind New Zealand.

Argentina, who trailed 15-9 at half-time, camped in the Springboks' half for much of the second period, but three missed kicks at goal by fly-half Santiago Carreras proved costly.

A breakaway try by fly-half Manie Libbok on 69 minutes became crucial as it extended the South African lead to a flattering 13 points.

But the Pumas never tired and tries from winger Mateo Carreras and scrum-half Gonzalo Bertranou reduced the gap to a single point.

Earlier on Saturday, New Zealand scored six tries to crush Australia 38-7 in Melbourne and claim the southern hemisphere title for the ninth time in 11 editions.

Much pre-match attention had focused on dynamic South Africa scrum-half Grant Williams as he prepared to make his first start after three appearances off the bench.  

But he was concussed after just 10 seconds, colliding with Argentina full-back Jean Cruz Mallia, having clearing the ball on a cold winter night.

Williams was stretched off and replaced by veteran Faf de Klerk, who helped the Springboks defeat England in the 2019 Rugby World Cup final in Japan.

Argentina captain and hooker Julian Montoya was another early casualty, but continued after a head injury was strapped. 

He left the field later in the half with his face covered in blood, but came back after changing his bandaging and blue and white hooped shirt.

- Pumas strike early -

Two successful penalty kicks by fly-half Santiago Carreras gave the Pumas a six-point advantage on 10 minutes as the hosts were slow to settle.  

A close-range Libbok penalty sailed between the posts to halve the deficit and the home team went ahead on 19 minutes through a try from lock Eben Etzebeth, winning his 112th cap.

Etzebeth and hooker Malcolm Marx combined in a clever lineout manoeuvre that ended with the second rower charging over near the corner flag.

Libbok failed to convert, but did add the extra points to a second South African try after 26 minutes as centre Damian de Allende touched down following a driving maul. 

Santiago Carreras, who was injured and temporarily replaced by Tomas Albornoz, returned to complete the first-half scoring with a penalty just before the break.

Before Irish referee Andrew Brace signalled half-time, however, there was another lengthy injury-induced break that ended with Argentine lock Lucas Paulos being carried off.

Santiago Carreras missed two kickable penalty attempts before an Argentine movement broke down and De Klerk sent Libbok clear to score a try he converted.

When Mateo Carreras scored in the corner, brother Santiago failed to convert, leaving eight points between the teams.

That margin was reduced to a single point when Bertranou scored beside the post and Santiago Carreras converted. 

Argentina and South Africa meet again next Saturday, in Buenos Aires, in a warm-up match ahead of the September 8-October 28 World Cup in France.

dl/dj