The Wallabies acknowledge it’s an emotional week for scrum guru Mario Ledesma as he helps them to derail the Rugby World Cup campaign of his countrymen.

Argentina loom as a huge threat for Australia in Sunday’s semi-final at Twickenham, having improved greatly since they copped a 34-9 home thrashing back in July from the Wallabies.

Ledesma, who won 84 Test caps with Argentina in a superb career spanning 15 years before retiring in 2011, knows their culture, style of play and passion for the game better than anyone in the Australian camp.

He’s also an immensely proud man who is understood to be uncomfortable with the spotlight being shone on him this week as his home country and employer do battle for a spot in the final.

“It’s going to be a very emotional week for him, obviously,” said coach Michael Cheika, who recruited Ledesma first to the NSW Waratahs and then to the Wallabies.

“He’s still very proud and I wouldn’t expect him to be any other way (because of) his time with Argentinian rugby.

“(But) he knows what we need to do.

“We’re pretty matter of fact about it all.”

Australia’s scrum has undergone vast improvement in a short time while Ledesma has worked his magic, since being appointed mid-year.

From a laughing stock to a genuine weapon in Cheika’s arsenal, the Australian set-piece has overcome many challenges but the scrum is traditionally Argentina’s strength and has the Wallabies on edge.

“We know it’s going to be difficult because their scrum’s been very, very good and their driving maul, strong forward platform (and) they’ve built on from that as well obviously,” said Cheika.

“I think (Ledesma’s) influence will come more just on what we’re doing.

“He hasn’t really spent a lot of time with those (Argentine) players in particular, because he hasn’t coached a lot of them or many of them at all.

“He knows the general philosophies but I think we all do from video and stuff like that, from what we see.

“His influence will be more about getting our players at the level we need to be competitive with those guys at set-piece time.”