Fullback Emiliano Boffelli scored Argentina’s only try two minutes into the second half, catching and grounding a fine kick into the All Blacks’ in-goal area by flyhalf Nicolas Sanchez.
The Gunners head coach was speaking after watching his side make it two wins from two in the International Champions Cup with a 3-0 victory over Fiorentina in Charlotte.
The first-quarter set the precedent for the rest of the match. It was end to end intensity with the Australian defensive pressure being matched by the South Africans.
United manager Ole Gunnar Solskjær was full of praise for Greenwood after the game but cautioned against expecting too much.
History was on South Africa's side heading into the clash having lost just once in the last 10 meetings in Johannesburg.
South Africa go into the clash off the back of a 58-47 loss to hosts England in what has been their only defeat of the tournament to date.
Both teams got the ball rolling early as Sharks flyhalf Curwin Bosch and Province fullback SP Marais scored penalties to lock it up at 3-3 after five minutes.
The Springboks on home soil should be good enough to beat Australia at Ellis Park, but the visitors are capable of springing a surprise if the Boks are not wary.
Former Mamelodi Sundowns defender Mzikayise Mashaba was among the new signings by the Port Elizabeth-based side.
They earned this opportunity after winning the Danone Nations Cup girls tournament that took place at Reiger Park, Boksburg in June.
