Australia will improve before they take on old rivals New Zealand in the World Cup final next Saturday, coach Michael Cheika said after the Wallabies defeated Argentina in the semi-final.

"I think we can improve again I think that is really important now," the coach said after the 29-15 victory at Twickenham.

Next Saturday's final will be the first ever between Australia and New Zealand.

"Tonight we can think we have given ourselves the opportunity to play in a World Cup final and we will work out how we are going to do it against a pretty dynamic team," was all Cheika would say of the looming match.

But the coach said the Wallabies could have been more decisive against Argentina and gave away too many penalties.

"We left the game a bit open which really suited them (Argentina). Initially we kept it a bit more structured which suited us," he commented.

"I am really happy with the lads' defence, they are a very very strong attacking team, they tore Ireland apart last week and we had to work hard to stop them working a try.

"Penalties are a part of the game and we gave away too many in the first half. We tried to rectify that in the second half. We did a little bit, but we still gave away a few too many."

Source: AFP