Johannesburg - The Proteas have some more injury news on the bowling front with Kagiso Rabada struggling with a stiff lower back. 

Rabada picked up the strain while bowling in Australia's first innings. 

He is expected to bowl in the second innings, but word from the Cricket South Africa (CSA) camp is that he will not be at his quickest. 

Morne Morkel, meanwhile, is also in a bad way as he continues to recover from the side strain that he picked up in the first innings. 

Morkel, playing in his last Test match, was heavily strapped on Monday morning and he has been taking pain killers to try and get through the discomfort. 

It leaves Vernon Philander as the only fit seamer in the Proteas attack as they look to win the fourth and final Test at the Wanderers

Philander does have a strapped groin, but that has been the case throughout the match.

That would help explain why captain Faf du Plessis has opted to keep batting in South Africa's second innings, despite the lead being well over 500. 

South Africa lead 2-1 in the series, and they will become the first side to beat Australia in a home Test series since re-admission if they avoid defeat in Johannesburg.