Mokoena vows to be fit for South Africa
Mokoena sustained the injury while helping his English Championship side Portsmouth FC to a 2-2 draw against Middlesbrough on Saturday, the South African Football Association said.
The team's doctor said the injury is "mild", and Mokoena said he is determined to play in Sierra Leone.
"I missed the last match in Freetown, where we lost 1-0, due to injury, but there is no way I will miss this one," the Bafana Bafana captain said in a statement. "I am going to play, that is if the coach selects me, but there is no way I am missing this trip."
South Africa lead Group G in 2012 qualifying after beating Niger 2-0 last month. Egypt and Sierra Leone are tied for second after a 1-1 draw in Cairo.