As the All Blacks prepare for a massive semifinal against the Springboks, I believe their halfback and captain Fourie du Preez poses the biggest threat.
After his move to Japanese club Suntory in 2012, he's the one player that the All Blacks haven't seen a great deal of in recent times. While the All Blacks and Springboks usually play each other twice a year, he hasn't played Steve Hansen's men since 2013, a rip-roaring 38-27 defeat for the Boks in Johannesburg. Before that it was in Port Elizabeth in 2011.
During his time at the Boks he has been considered as one of the best halfbacks in the game. He's achieved a great deal, including winning a World Cup in 2007, so he's been to the coalface plenty of times. He knows what it takes.
He hasn't been playing for the Boks lately so for the All Blacks he changes the dynamic of his side. He's very good at controlling the game and he doesn't just do it with his kicking game. He has a running game which we saw last weekend against Wales when he scored the match-winning try after a nice assist from No8 Duane Vermuelen.