Malcolm Marx scored two tries in the second half to lead South Africa to a 30-12 victory over Australia in rainy Perth.

After a tight first half, the Springboks asserted their dominance to make it two wins from two in the Rugby Championship ahead of their meeting with New Zealand next week.

Noah Lolesio's penalty gave Australia the early lead, but they could not hold onto it for long as Sacha Feinberg-Mngomezulu equalised moments before Aphelele Fassi latched onto a long kick to touch down the first try.

Lolesio slotted in two more kicks only to miss another on the stroke of half-time that would have given the Wallabies the lead.

They were punished for it after the break as Marco van Staden and Malcolm Marx twice touched down to maintain South Africa's perfect start.

Though it was a marked improvement for the Wallabies from their opening-day performance in Brisbane, Joe Schmidt still has work to do to get them ready for Argentina next weekend. 

Data Debrief: Springboks extend Australian run

South Africa have now won each of their last three Test matches against the Wallabies in Australia. The last time they recorded a longer such winning run was a four-match span from July 1971 to July 1993.

Though Australia have suffered back-to-back defeats, they showed more of a fight. Last week, it took them 75 minutes to score, compared to just three this time around.