Dave Rennie has made the striking claim that the four-Test Rugby's Greatest Rivalry series presents a harder challenge than a Rugby World Cup campaign — higher praise for the Springboks than any ranking or trophy haul conveys. After three comfortable tour wins against the franchises, Rennie is under no illusions about what changes on Saturday at Ellis Park. His tactical read is pointed: the Boks lead the world in high-ball retention, 22-entries, and points-per-entry — meaning New Zealand's margin for defensive error is almost zero. Discipline and execution, he argues, are the levers that determine whether the All Blacks can limit the Springboks' access to their own 22, because once they're in there, the conversion rate is brutal. He also acknowledges the Boks can play expansively when they choose to — so the All Blacks can't simply defend the physical game alone.