With the three-match series set to come to an end on January 28, a four-week absence would see Steyn miss the rest of the Tests.
South Africa have picked up four fast bowlers including Dale Steyn and a spinner Keshav Maharaj. He is unlikely to bowl again in the current match, and may bat if needed.
Editorial team of CricketCountry.
"Understandably he was disappointed, but he will try his best to recover as quickly as possible. It also means he could be out of the series", said South African team doctor Mohammed Moosajee. "You could see how much he was enjoying himself out there".
The 34-year-old paceman, regarded as one of the game's great fast bowlers, has been plagued by problems with that shoulder and only played eight Tests in three years before his return this week. This was his first Test after the comeback.
He only returned to competitive cricket during the recent RamSlam T20 Challenge for the Titans, and bowled two spells for the South African Invitation XI with a pink ball at Boland Park last month.More news: The Weeknd, Beyonce and Eminem to headline Coachella 2018
While Steyn was impressive in taking two for 51, Philander was exceptional in giving the batsmen nothing and taking three for 33, and Morkel worked hard for two for 57, there is nothing quite like watching Rabada bowling at full tilt.
Injuries seem to be following Dale Steyn like his own shadow.
Moosajee emphasised that the injury was in "no way related to his bowling loads or previous injuries", of which there have been several in the past two years.
Moosajee said it was important to note that it was a freakish type of injury and had nothing to do with his injury history or workload in the match.
"We will have a leading ankle surgeon look at him tomorrow and get an opinion".
Having been roughed up by a barrage of short-pitch bowling from the excellent Rabada (3-34), the latter ended Pandya's stay at the wicket as he induced an edge to De Kock.The rest of the batsmen found it hard to score against the fast, accurate home bowling. "We would, though, like him to be non-weight-bearing".