Australia got out to a galloping start with a try after only two minutes. But any thoughts that the fancied Australians would run rampant over their South American opponents were equally quickly given the lie.

Although Australia scored three tries in the first half, Argentina countered the Wallabies' attacking approach with five penalties by Nicholas Sanchez. With 26 minutes to go, the South Americans only trailed by seven points.

But Adam Ashley-Cooper came through with his third try of the match to seal the win for Australia. They now advance to face arch-rivals New Zealand in next Sunday's final.

"It was a tough game and we knew it would be," Australia's captain Stephen Moore said after the Argentina match. "We had to defend a lot. We have an opportunity in a final now. That took a fair bit out of the tank. We know the task next week is huge, we have to recover well."

New Zealand overcame South Africa 20-18 in London on Saturday to advance to a record fourth World Cup final.