Steyn's bowling in the recently-concluded third and final Test against Australia in Cape Town was affected by the strain as the tourists went on the win the match and the series.
He will return for the last of the three-match series in Pretoria next Friday and is still earmarked to compete in the World Twenty20 in Bangladesh later this month.
South Africa also have doubts over the fitness of Wayne Parnell and Beuran Hendricks for the first game of the T20 series against the Australians in Port Elizabeth on Sunday.
Both will undergo fitness tests on Saturday to determine their availability.
Parnell sustained a strain to his right groin during the second Test against Australia, while Hendricks is recovering from a side strain sustained in domestic competition.
Kyle Abbott had been added to the South Africa squad as cover, Cricket South Africa added.
Image: Dale Steyn
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