Battle of scrum-halves Aaron Smith and Fourie du Preez key to All Blacks-Springboks showdown

The All Blacks and Springboks clash again in rugby union's biggest rivalry tonight when New Zealand speed takes on South African muscle in a Rugby World Cup semi-final at Twickenham.

Their coaches, Steve Hansen and Heyneke Meyer, have been playing mind games all week but now it gets serious - a battle of wits between All Black skipper Richie McCaw and his Springbok counterpart Fourie du Preez, a race to get into the record books featuring New Zealand wing Julian Savea and South Africa flyer Bryan Habana.

Savea and Habana share the record with All Blacks legend Jonah Lomu for the number of tries in a single World Cup - eight. Habana is level with Lomu for the overall World Cup record, 15.

Something is likely to give in only the fourth World Cup clash - including the epic 1995 final won by the Springboks - between the two sides who have dominated rugby over the past century.

While there will be plenty of forward strength on show, the 91st meeting between the union superpowers could be decided by rival scrum-halves Aaron Smith and Du Preez.

Smith will hope his bullet pass can keep play moving at a frenetic pace to suit the All Blacks' lethal back three trio of Savea, Nehe Milner-Skudder and Ben Smith, with speed off the bench allowing the All Blacks to maintain a high tempo for the full 80 minutes.

Du Preez, the Springboks' master tactician, will work off the opposite plan, keeping the ball close for Duane Vermeulen, Schalk Burger and the rest of a heavy pack to relentlessly ram their way forward.