"Morkel has hurt his foot and he is a bit of worry for us," Mickey Arthur, the South African coach, told reporters on Saturday.
"He will have a fitness test on Sunday because we would like to make sure he is 100 per cent fit."
Test veteran Shaun Pollock, who was told on Friday he would not be playing in the first Test from Monday as team management wanted to try out younger players, may yet be included.
"Now as the situation stands, Pollock might still play the Test. Because of Morkel's niggle, he might not be fit for the Test," said Arthur.
He defended the decision to rule out Pollock, saying it was time South Africa started a rebuilding process.
"We have batting depth, it is time we built on our bowling strength."