South Africa captain Siya Kolisi is in doubt to lead his country's Rugby World Cup defence because of a knee injury, according to a report.

South Africa's Independent Newspapers group reported that Kolisi sustained a partial tear to the anterior cruciate ligament in his right knee playing for his Durban-based Sharks against Ireland's Munster on Saturday.

Kolisi has seen two specialists, one of whom has recommended surgery, Independent Newspapers said.

The report said Kolisi would consult a third specialist on Tuesday.

The Sharks said Kolisi was consulting doctors over the injury but have not released a prognosis.

Source: Stuff.co