Ntini damaged his hamstring and tendons in his left leg

"Sydney is widely considered as a spin-friendly wicket," said chief selector Haroon Lorgat - boosting slow bowler Botha's chances of a debut.

Paceman Makhaya Ntini (knee) and all-rounder Justin Kemp (shoulder) have both been ruled out of contention.

The Proteas were beaten at in Melbourne in the second Test of three to be 1-0 down with just one match to play.

"I think Johan will give us more options to consider going into the Sydney Test with two spinners a possibility," said Lorgat.

Botha made his first one-day international appearances for South Africa in India.

He has a fine first-class record, averaging 32 with the bat and 27 with the ball.

It will be interesting to see who replaces him From NN Have your say on TMS

Ntini will return home to South Africa to receive medical treatment to his injured knee.

"I cannot over-emphasize the importance of not taking risks with injured players, said Lorgat.

"From a selection perspective, we want him to have medical attention and be one-hundred percent fit for the home series against Australia."

A 61-Test veteran, Ntini took nine wickets in the first two Tests, including figures of 5-64 in the opening match in Perth.

According to research published on Thursday, he is South Africa's most popular sportsperson, the first time a cricketer has taken the accolade.

He is fourth in the latest LG ICC rankings, behind Sri Lanka's Muttiah Muralitharan and Australian duo Glenn McGrath and Shane Warne.