South Africa's World Cup winning captain Siyi Kolisi has emerged as a doubt for this year's title defence amid reports he incurred a cruciate ligament tear in the Sharks draw at home to Munster in the URC last weekend. Reports of partial tear to Kolisi’s anterior cruciate ligament and a damaged meniscus dominated local media on Tuesday, although there has been no confirmation from him or his club. The Springbok captain is being advised to have surgery on a knee injury and would then likely miss South Africa’s defence of the World Cup in France from September. South African media reports said the 31-year-old Kolisi had been advised by one of the two specialists he has consulted to have an operation to fix the problem, which would mean a spell on the sidelines of up to nine months, but was seeking a third opinion.