South Africa's opening bowlers are the top-ranked in tests, with Vernon Philander at No. 1 and Dale Steyn at No. 2.
But Johnson's figures from the Ashes -- 37 wickets at an average of 13.97 and with a best of 7-40 -- show he is in lethal form. Ryan Harris took 22 wickets and Peter Siddle 16, while Australia also has a threatening spinner in Nathan Lyon and bowled England out for less than 200 in six of 10 innings in the series.
South Africa continues to struggle to find a consistent slow bowler to complement its fast bowling trio of Philander, Steyn and Morne Morkel, and dropped Imran Tahir for this series.
Also permanently missing for South Africa for the first time in nearly two decades is Jacques Kallis, the veteran allrounder who retired after the series win over India late last month.
South Africa has to replace its best player ever in this contest and find a new balance, while Australia is completely settled after picking the same 11 throughout the one-sided Ashes win.
“No team will ever be able to replace such a great player,” Clarke said of Kallis' absence.
“I think the South African batting lineup is extremely strong even without Jacques being in there but Jacques would be a big loss to any team.”
Australia is up against a five-year unbeaten run by South Africa.
