Henry, a World Cup-winning coach with New Zealand and now Argentina's consultant coach, said the Wallabies were still favourites against the Pumas in Perth despite their Rugby Championship woes.

The Wallabies have won just one of their past six Tests and McKenzie is yet to record a win as coach. But although McKenzie was considering dumbing down his attacking tactics, Henry said the Wallabies needed an expansive style if they wanted to dominate Test rugby again.

''[The Wallabies] are struggling, aren't they. The Wallabies were the best team in the world at the turn of the century. It will come again it's just a matter of when,'' Henry said. ''A couple of wins under Ewen will put that right … they'll gain some confidence.

''When they were the best team in the world, they played an expansive game … it will happen again. Rugby is a simple game. It doesn't take a couple of years to build a team, it can take a week. Hopefully not this week.

''[Attacking] is the way they should play in my opinion. That's their mentality and skill level, you're not going to win by playing chessboard rugby, kicking in the air and chasing it.

''That's not the way Australians play. I think they're trying to play the right way.''

The Pumas are trying to beat the Wallabies for the first time since 1997 and Australia's struggles have opened the door for an upset. With McKenzie still finding his feet and the team down on confidence, the clash in Perth is the perfect chance for the Pumas to pounce.

Henry has been working with the Argentina side as a consultant for the past two Rugby Championship seasons after guiding New Zealand to a World Cup triumph in 2011.

The Wallabies made the drastic decision to axe captain Will Genia this week.

Henry believed it was McKenzie's way of ''trying to find the button to reignite'' the champion halfback and help the side get confidence. ''The [series against the British and Irish Lions] probably knocked [the Wallabies'] confidence,'' Henry said on Thursday.

''They're still recovering from that and struggling a bit. I thought [Genia] was the best halfback in the world a year ago. He's not playing as well as he has and I'm not sure why, but he's an outstanding rugby player.''

Henry will rejoin the Pumas team in Argentina next week.

There is no professional rugby union in Argentina and Henry hoped injecting more Pumas into Super Rugby was an option to develop the standard of play.

Adding them to the Rugby Championship and regular competition against South Africa, the Wallabies and New Zealand has improved their international ability.

''When [Henry] arrived last year, he said, 'If you attack the way you defend, you could be world champions,' '' veteran Pumas inside-centre Felipe Contepomi said. ''We defend with a lot of mentality, a lot of passion. But sometimes we don't have the same belief in attack.

''So we are trying to change that. He added a lot of confidence and knowledge in the way to attack. He can add to our rugby culture.''