They got far more of a battle than they were expecting, but defending champions South Africa still won through to the semi-finals of the World Rugby Classic last night after beating a spirited and much-improved America at the National Sports Centre.

With yet another chilly north wind buffeting the hundreds of spectators who lined the flood-lit North Field, the South Africans predictably sprung out of the traps at a frightening speed, surging into an early 12-0 lead thanks to two tries from winger Jan Harm van Wyk.

Powerful up front and quick out wide, it looked at that stage like the South Africans would rack up a cricket score against a country where rugby is marginally less important than football.

But to their great credit, the Americans mounted an excellent and sustained fightback, with flanker Mike Stanaway scoring in the 17th minute before Malakai Tabvuya touched down to bring the scores to 12-10. A converted try from the South Africa?s Andries Fourie, followed by a US drop goal from Tabvuya took the score to 19-13 at the break, before the Americans emerged to score right after half time to get within a point.

A superb back line move from the South Africans in the 41st minute ended in a try for Van Wyk ? his third of the night, and after that the favourites turned on the style with two further tries from flanker Tiaan Strauss and prop Adrian Garvey ? the latter capped 15 times for the Proteas.

With victory well beyond their grasp, the US carried on fighting nevertheless ? with pacey winger Jason Raven registering his first try of the night with a brilliant solo effort from just over the halfway line.

The Boks now move on to play southern hemisphere rivals Australia in Thursday night?s semi-finals and captain Johan Kapp was well aware they are going to have to play better to become the first team ever to win three Classic titles in a row.

?It?s going to be tough against the Aussies, no question,? said the skipper, who is making his seventh appearance at the Classic.

?Tonight was obviously the first time we have played together as a team and also the Americans were a lot better than they have been in previous years and gave us a real test.

?But we always knew that if we got the ball out wide, with our pace they would not be able to handle us and though we slacked off at times, the victory was pretty comfortable in the end.?

In the first match of the night, three tries from David Grimmond sealed a relatively straightforward win for the Aussies, who will be looking to win their first Classic title this year.

Canadian flanker Rob Waddell scored their only try, and Canada now go on to play the US in the plate semi-final on Thursday night.