South African fast bowler Makhaya Ntini [ Images ] has injured his knee and will not bowl again during the second Test against Australia [ Images ] and has been ruled out of the third Test in Sydney [ Images ], a team spokesman said on Thursday.

The 28-year-old suffered a torn medial ligament in his left knee on Wednesday and underwent a fitness test on Thursday.

A team spokesman said Ntini had been able to run, but felt sharp pain when he attempted to land on his front leg as he bowled.

Andre Nel [ Images ] and Shaun Pollock [ Images ] opened the bowling on day four for the Proteas.

Ntini is expected to be able to bat in South Africa's [ Images ] second innings, if required.

The third and final Test begins on January 2.