Cubelli, who is poised to move to Australian rugby with the ACT Brumbies next year, will clash against the Wallabies in the World Cup semi-final at Twickenham on Sunday (Monday morning AEDT).

The 26-year-old will share the halfback duties with Martin Landajo in the biggest match of their careers as they attempt to end Australia's campaign.

The Pumas are traditionally known for their hard-nosed forward play. But they have opened their arms at the World Cup to get their electric back line into play.

It has put them at the top of the World Cup statistics for offloads thrown and they sit behind only New Zealand in points and tries scored.

Coach Daniel Hourcade has told the players: "we play with our heart in our hand" and it's an ominous warning to the Wallabies.

"I think it's very important to play without fear. It is very difficult to achieve in a national team where there's a lot of pressure," Cubelli said.

"But I think we could work [on] it during the Rugby Championship when we were playing the best teams in the world and we still tried to play as their equal, and to have an ambitious rugby intention.

"It's great when teams really express as a team and individuals. It's great when all individuals are expressing the same objective. I think good things come from that."

Argentina smashed Ireland 43-20 to book their spot in the semi-final against Australia.

They are playing in the World Cup semi-final for the second time in eight years and they will sniff a weakness in the Wallabies after they stumbled against Scotland last weekend.

The Pumas have beaten Australia just twice since 1997, but one of those wins came last year and triggered a nightmare period for the Wallabies, which led to Ewen McKenzie quitting as coach.

Cubelli has been linked to a move to the Brumbies as a replacement for former Test halfback Nic White next year.

But his immediate focus is on securing a World Cup final berth.

"Yes we are lucky to have great rugby players, but we are even more lucky to have great friends and great people," Cubelli said of the Pumas' title hopes.

"It maybe comes with the way we are educated in our clubs in Argentina. Rugby in Argentina is amateur, first of all in most of the clubs you are educated as a good person, a good teammate and afterwards as a good player.

"Because sometimes we don't have the structures, all the coaches study the game of course but at some points we don't have the resources.

"We might not have fantastic resources, but we have great human resources. That's what we have and we have to do that well. If we don't have that then we can't compete."