South African fast bowler Dale Steyn left the field with a bruised left heel on Saturday, the second day of his first Test match in more than a year.
Steyn pulled up three balls into his 18th over after taking two for 51 in the first Test against India at Newlands.
A team spokesman said the injury was being assessed and treated.
Steyn, 34, had not played in a first-class match since suffering a fractured shoulder in a Test in Australia in November 2016.
He was included in a four-man pace attack for the India Test despite coach Ottis Gibson expressing concern about risking him because of a lack of match practice.
In the only cricket since his injury, Steyn bowled 18 overs in five Twenty20 matches for his franchise, the Titans, as well as 12 overs in a low-key appearance for an Invitation XI against the touring Zimbabweans in December.
