The loose forward earned his first Test start in Saturday's defeat of South Africa, coming from outside the 23-man squad as a late replacement for David Pocock (neck).

It capped a crazy year for the Crusaders talent, who earned a late release from New Zealand Rugby to debut for Australia against Ireland in June.

Teammates had hoped to crack the softly-spoken 102kg powerhouse but ahead of Saturday's clash with Argentina on the Gold Coast - and a possible seventh cap - it appears they have failed.

"Na, not really, I'm still pretty quiet," he blushed, nodding when it was offered that actions speak louder than words.

Samu isn't without a sense of humour though, admitting that the Irish anthem was "quite catchy" and that Crusaders teammate Joe Moody had locked onto him during the Bledisloe Cup opener's pre-game haka.

"I was trying to keep a straight face .... (Moody was) smiling at me while he was doing it," the 26-year-old said.

"I just stepped in to hide behind one of the tall boys so I didn't have to look at him."

Born in Melbourne and a product of the Randwick Rugby Club, Samu will play for the Brumbies next season and is rated highly by Australian coach Michael Cheika.

Eligible to play for both Australia and New Zealand, Samu insists he was never approached by the All Blacks and that the potential to play for the Wallabies at next year's World Cup was a major factor in the move.

"A year ago I was playing Mitre 10 (Cup, in New Zealand) and thought I'd still be in New Zealand, actually," he said.

"It's all happened so quick, but I definitely think we can win the World Cup."

Pocock is likely to be fit for Saturday's game, as is fullback Israel Folau (ankle) meaning Samu would be expected to drop back to the bench.

Starting or not, Samu remains upbeat.

"Defence wins games. If we nail the few defensive things we slipped up on I think we'll go alright this weekend," he said.

Australian Associated Press