Ireland has scored a bruising 13-8 win over defending champions South Africa at the Rugby World Cup, with Australia-born winger Mack Hansen scoring a try for the top-ranked side. 

Hansen, who grew up in Canberra and previously played for the ACT Brumbies, crossed for Ireland's sole five-pointer in front of a huge contingent of Irish fans at the 80,000-capacity Stade de France in Paris.

The Daramalan College product qualifies to play for the Irish through his Ireland-born mother and appears for Connacht at the club level in the United Rugby Championship.

The former Junior Wallabies representative found some rare space out wide to score in the 33rd minute, helping Ireland to a 7-3 lead at half-time.

But the Irish had to withstand a barrage of Springboks pressure in the second half amid a raucous atmosphere.

The Springboks' only try came from winger Cheslin Kolbe in the 51st minute, but they missed the conversion and three penalty goal chances.

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Johnny Sexton converted Hansen's try and kicked a penalty goal, while Jack Crowley added three points from the tee in the 77th minute to ice Ireland's win after they led 10-8 late in the match.

The Springboks were on top for considerable spells but paid the price for poor goal-kicking from fly-half Manie Libbok and scrum-half Faf de Klerk, who missed a combined four of five and left 11 points in the wind.

After Crowley slotted his 77th-minute penalty goal, the Springboks needed a try to draw and a converted score to win.

The Springboks earned a lineout 10 metres from the Irish line but the maul was smothered and they could not recycle the ball quickly enough before referee Ben O'Keeffe called play up and the match was over.

Alongside Hansen, Ireland's squad featured another Canberra-born player in prop Finlay Bealham, who came off the reserves bench in the second half.

Ireland, which has never advanced past the World Cup quarterfinals, will be odds-on to top Pool B after claiming a 16th Test win in a row.

The result gave the Springboks their first World Cup defeat in nine matches and they will likely have to beat Tonga in their final pool match to guarantee a quarterfinal berth.

It was the second time Ireland has beaten the Springboks in the past 10 months and its first World Cup victory over the three-time winners.

Ireland faces Six Nations rival Scotland in its last pool match at Stade de France on October 8 AEST.

In other results, Georgia and Portugal drew 18-18 in Pool C, which also features the struggling Wallabies, who play Wales in a crucial match on Monday morning AEST.

England thrashed Chile 71-0 in their Pool D encounter.

AP/ABC