Gold Coast - Michael Cheika says Argentinian counterpart Mario Ledesma is like family, but the deadly serious Wallabies boss is in no mood for banter as he faces his former forwards coach on Saturday.
The two men worked side-by-side for the Waratahs and then Australia until the end of the 2017 season when Ledesma was appointed coach of Super Rugby side the Jaguares and then the Pumas.
They are close, but the friendship has been temporarily put aside, and Cheika was not impressed by assistant Wallabies coach Stephen Larkham joking with reporters this week about Ledesma.
"I'm not that into it, if you know what I mean," he said of the banter.
"I get the joke and everything but like I said, there won't be any joking on Saturday. It's going to be a big confrontation."
Cheika was speaking after Larkham told media, tongue in cheek, that Ledesma "struggled as an assistant coach... I can't see how he's had the limited success he's had already".
The Wallabies go into the Rugby Championship clash on the Gold Coast upbeat after beating South Africa 23-18 last weekend to end a four Test losing streak.
They also have a mental edge, having beaten the Pumas in 15 of their last 16 Tests.
Despite being odds-on favourites, Cheika is taking nothing for granted with Argentina much improved under Ledesma's stewardship.
They upset the Springboks 32-19 in Mendoza recently and put up a spirited performance against the All Blacks last weekend.
"I don't think anyone is under the illusion that we don't need to work harder this week than the week before," said Cheika. "This is a pivotal Test for both nations."
The Wallabies will be without skipper Michael Hooper, who pulled out on Friday with a hamstring injury.
But they have been boosted by the return from injury of breakdown specialist David Pocock, who takes over as captain, and Israel Folau, who will start on the wing rather than his favoured fullback spot for the first time in five years.
It is a gamble by Cheika, who has opted to keep Dane Haylett-Petty in the number 15 jersey after two standout displays in Folau's absence.
The tactical shift follows veteran Bernard Foley being dumped for the Springboks clash in favour of Kurtley Beale at flyhalf and Matt Toomua at inside centre, with the combination retained for Argentina.
Pocock said the Wallabies were wary of Argentina under Ledesma, who he described as "a great man".
"He mixes an abrasive big forward pack with some real flair out wide, so you've really got to cater for everything in defence," he said.
"And they've got some really good guys on the breakdowns. It's going to be a huge challenge for us."
Argentina's scrum has long been considered the rock their game is built around, but it struggled against the All Blacks, with Ledesma, himself a former hooker, admitting it had been "torn apart".
In a bid to fix their problems, prop Santiago Medrano has been brought in to the starting XV for Garcia Botta and blindside flank Pablo Matera returns in place of Tomas Lezana.
After resting last weekend, Gonzalo Bertranou is back at scrumhalf with Martin Landajo relegated to the bench.
Lock Guido Petti, who will be playing his 40th Test, said they were expecting a "complicated game".
"They have a very dynamic game, a lot of variants and attack options," he said.
"We have to try and counteract that by keeping the ball and our formation. If we do that, we will have a great game."
15 Dane Haylett-Petty, 14 Israel Folau, 13 Reece Hodge, 12 Matt Toomua, 11 Marika Koroibete, 10 Kurtley Beale, 9 Will Genia, 8 Pete Samu, 7 David Pocock (captain), 6 Lukhan Tui, 5 Izack Rodda, 4 Rory Arnold, 3 Allan Alaalatoa, 2 Tatafu Polota-Nau, 1 Scott Sio
Substitutes: 16 Folau Faingaa, 17 Sekope Kepu, 18 Taniela Tupou, 19 Adam Coleman, 20 Ned Hanigan, 21 Nick Phipps, 22 Bernard Foley, 23 Jack Maddocks
15 Emiliano Boffelli, 14 Bautista Delguy, 13 Matias Moroni, 12 Jeronimo de la Fuente, 11 Ramiro Moyano, 10 Nicolas Sanchez, 9 Gonzalo Bertranou, 8 Javier Ortega Desio, 7 Marcos Kremer, 6 Pablo Matera, 5 Tomas Lavanini, 4 Guido Petti, 3 Santiago Medrano, 2 Agustin Creevy (captain), 1 Nahuel Tetaz Chaparro
Substitutes: 16 Julian Montoya, 17 Santiago Garcia Botta, 18 Juan Pablo Zeiss, 19 Matias Alemanno, 20 Juan Manuel Leguizamon, 21 Martin Landajo, 22 Bautista Ezcurra, 23 Juan Cruz Mallia