The Rugby World Cup semifinal between the All Blacks and Springboks is littered with mouth-watering individual match-ups but the contrasting stories of Aaron Smith and Fourie du Preez have added something a little extra at half-back.

Smith, the standout No.9 of the past few years, has arguably grown into a more important figure for the All Blacks than Dan Carter, with the diminutive Highlanders scrum-half able to adapt to an array of fly-half partners throughout the veteran No.10's injury run.

And then there's Smith's ability to change the momentum of a match all on his own, just as he did throughout the Super Rugby season and then again in the All Blacks' opening World Cup clash with Argentina via a 57th-minute five-pointer.

On the other side of the coin lies Du Preez, arguably the best No.9 of the past decade and a player Springboks coach Heyneke Meyer was so keen to use at the World Cup that he afforded him every opportunity to recover from a debilitating back injury -- one he continues to battle today.

Injuries to Jean de Villiers and Victor Matfield have seen Du Preez take on the Springboks captaincy as well, and there was no bigger skipper's play than Du Preez's 77th-minute match-winner against Wales last weekend.

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Aaron Smith passes to Nehe Milner-Skudder during a New Zealand All Blacks training session © Getty Images

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It was the kind of blind-side dart all young half-backs dream of making, and one Smith is well accustomed to.

"He was an idol of mine when I was growing up watching him play for the Bulls," the All Blacks half-back said on Thursday.

"He's a fantastic player, leading by example. Match-ups for half-backs are a bit different, less about smash'n'bash like other positions; more about how you get your team around the park.

"We've identified him as a key figure. I can't wait to play him."

Both men will be central to their respective team's hopes of reaching another Rugby World Cup final, with Smith desperate for a chance after missing the All Blacks' squad four years ago and Du Preez looking to add to his 2007 Webb Ellis crown.

With Smith at 26 years of age and 45 Tests, and Du Preez at 33 and 75 Tests, there is a decent gap in experience but the same cannot be said for class. For that there is very little between the two.

And there is little doubt that Smith will one day be remembered as the standout No.9 of this century's second decade, just as Du Preez is from the first.

Whether Smith's ascension into the rugby almanacs is tinged with a World Cup speedbump, only Du Preez can determine.