Better execution in the South Africa 22 would have resulted in a famous win, but Argentina coach Michael Cheika insists his side are growing in stature following their narrow 22-21 Rugby Championship defeat at Ellis Park on Saturday.

In the last year Argentina have won in England, New Zealand and Australia, and fell agonisingly short of adding world champions South Africa to that impressive list six weeks away from the start of the Rugby World Cup in France.

But there is no question they are gathering momentum following their 34-31 win in Sydney a fortnight ago and another accomplished performance in Johannesburg, where they outplayed their hosts for large parts of the game, but this time lacked the knockout blow.

"We played better than last week against Australia, although we didn't get the result we wanted," Cheika told reporters. "We are going to improve the maul and the scrum, but we had more possession and were a lot in South Africa’s 22 without finishing.

"In the first half we had two or three unnecessary offside penalties, so we have to be more disciplined, make good decisions and not give easy an easy way into our half.

"If we are in their 22, or near the tryline, we have to work out the best strategy."

Argentina will have another crack at the South Africans in a World Cup warm-up game in Buenos Aires on Saturday, with the Springboks having selected a squad from their wider pool of players for the encounter.

"We can't wait to play the rematch, because the group is in a very good physical and mental moment," a confident Cheika said.

Argentina have England, Japan, Samoa and Chile in their World Cup pool. They are also scheduled to meet Spain in a warm-up fixture on August 26.