TWICKENHAM, London -- One chance was all South Africa had at Twickenham on Saturday, and, fortunately for them, the ageless Fourie Du Preez was good enough to take it.

South Africa are the first side through to the Rugby World Cup semifinals after a gripping 23-19 win over a Wales side that yet again defied their horror injury run but suffered one defensive lapse. And it hurt them badly.

Unlike Wales' nine-point defeat to the Wallabies last week, the Dragons themselves were forced to defend phase after phase from the Springboks for much of the second half. And they did so with relative ease -- largely due to the fact that this was a typical Springboks performance built on one-out running. Time after time, the likes of Schalk Burger, who topped the run charts with 26 but can't have made more than 30 metres, Lood de Jager, Francois Louw and Duane Vermuelen rolled off du Preez and thundered into the Welsh wall.

There were the obligatory high balls while fly-half Handre Pollard took the line on a few times but never managed even to poke his nose through. On the fleeting occasions that Damian de Allende and Jesse Kriel did see the ball, the centre duo ducked and weaved but also had little success in opening up the Welsh defence. JP Pietersen may well have caught a cold.

Bash, barge; bash, barge. It was one-out rugby at its finest, and the Springboks to a tee.

And for all but the final five minutes, it looked like they would live to regret it. Heyneke Meyer's side barely troubled the Welsh line before the break, and still they couldn't find a way through even after owning possession and territory for much of the second stanza, .

But then No.8 Duane Vermeulen picked up at the base of a scrum 15 metres in from touch and, opted to explore the blindside. Vermeulen, who made the most metres of any Springboks player, with 84, stood in the tackle and delivered a delightful little flick pass to Du Preez, who outsprinted Alex Cuthbert to dive into the corner.

One chance. One try.

Fourie Du Preez of South Africa scores despite the diving tackle of Alex Cuthbert © Getty Images

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It was only right, too, that the veteran No.9 -- who now plays his rugby in Japan -- was there to provide the match's defining moment. Du Preez had been a composed presence in the 74 minutes prior, and drew the ultimate set of compliments from Meyer post-match.

"I've worked with him since he was 19, he's the most astute rugby player I've ever coached," Meyer said. "He's a rugby and a tactical genius and I really mean this, if you look at South Africa playing well over so many Test matches, Fourie was always the guy organising the teams, always the guy making the tactical decisions.

"And if you look at all the games where South Africa played well, he played. And he don't always get the credit for that and I'm really happy for him."

If Du Preez is a tactical genius, then Meyer himself is a tactical creature of habit. There is no mystery to this Springboks side.

They have reverted to a style of rugby that has served them so well over the years but one that involves them grinding opposition sides into the ground with wave after wave of one-out runners.

Their semi-final opposition will know exactly what's coming their way.

And Du Preez might not be there to rescue them once more.