Argentina will sense a great opportunity to earn their first victory of the Rugby Championship when they face Australia on Saturday.
After two defeats to world champions New Zealand to open their campaign, the Wallabies came from behind to beat the Springboks last week, giving under-siege coach Robbie Deans much-needed breathing space.
But the 26-19 win in Perth came at a cost with skipper Will Genia badly injuring his knee. First-choice captain James Horwill is also sidelined, along with his successor David Pocock.
The Wallabies start as favourites for the Gold Coast clash but will be wary of a Pumas outfit that pushed the All Blacks hard for 60 minutes last weekend before eventually fading to lose 21-5.
Australia insist they will not underestimate the Argentinians, who held the Springboks to a 16-16 draw in Mendoza last month in the inaugural championship.
Sharpe, 34, who originally announced he was going to retire earlier this year, is the only Australian player to have faced the Pumas, and flyhalf Quade Cooper admitted the Wallabies had little knowledge of the South Americans.
"There's been a lot of tape-watching this week for a lot of the boys," Cooper said.
"We don't know much about them and no one in the team, except for Sharpy, has had the opportunity to play against them.
"Their unpredictability is a big strength... and also their forward pack. They're definitely a team we're not taking lightly at all. They're going to throw a lot at us."
The enigmatic Cooper will be faced with extra responsibility following the season-ending knee injury to scrumhalf Genia last week.
Melbourne's Nick Phipps comes into the side at scrumhalf in one of three changes to the Wallabies team from the Springboks match.
Waratahs lock Kane Douglas will make his Test debut in place of injured Sitaleki Timani, while inside centre Pat McCabe returns from injury, with Berrick Barnes dropping to fullback and Kurtley Beale to the bench.
Sharpe, who had intended to retire at the end of the Super Rugby season before an injury to Horwill led to his call-up, takes over from Genia as captain. He has captained Australia twice before.
Argentina's Leicester-based front-rower Marcos Ayerza, who is in the Pumas squad but will not be playing Saturday, said Genia's injury would be a huge loss for the Wallabies.
"When you lose a key player like a number nine or ten, a captain, it makes a large difference and we hope to use that to our advantage," he said.
"It's a huge task for us to compete with Australia. We are desperate to get our first win and we know that if we are not at 110 per cent that will not happen."
Pumas coach Santiago Phelan has made two backline changes to the team that lost to the All Blacks, dropping scrumhalf Nicolas Vergallo and fullback Martin Rodriguez.
Martin Landajo comes in for Vergallo, while the exciting Lucas Gonzalez Amorosino takes over at fullback.
This could mean that the Pumas will look to play a more attacking brand of rugby than they have against the All Blacks and the Springboks so far, but with an unchanged pack they are not likely to veer to far away from their strengths.
They have based their approach in the competition on a very accurate kicking game, with committed defence and a powerful pack, so they will try to take the Wallabies on up front before sending it wide.
Players to watch:
For Australia: The dynamic Michael Hooper was everywhere against the Springboks last week, and veteran skipper Nathan Sharpe will play a big leadership role as Argentina are likely to attack Australia in the tight exchanges. In the backline the Wallabies will look to Quade Cooper and Digby Ioane to spark something on attack whilst Berrick Barnes will have to adapt quickly to life at fullback.
For Argentina: New fullback Lucas Gonzalez Amorosino is an exciting runner who can break a game open, but classy flyhalf Juan Martin Hernandez will also want to control the game with his measured boot, so it will be interesting to see how the Pumas use both of those weapons. In the forwards captain Juan Martin Fernandez Lobbe will be key once again and lock Patricio Albacete will play a big role in the set phases.
Head to head: The duel for the ball on the ground between Michael Hooper and Juan Manuel Leguizamon should be intense and in the front row Rodrigo Roncero and Ben Alexander are both coming off solid performances so the battle between the Argentine loosehead and the Australian tighthead at scrum-time should be good. Both teams have new fullbacks and it will be vital for them to settle down whilst the contrasting styles of the flyhalves should also make for a good contest.
2003: Australia won 24-8 in Sydney
2002: Australia won 17-6 in Buenos Aires
2000: Australia won 32-25 in Canberra
2000: Australia won 53-6 in Brisbane
1997: Argentina won 18-16 in Buenos Aires
Prediction: The Pumas are growing in confidence and will see Australia as vulnerable, but the home side should be able to hold them off to win by about five points.
Australia: 15 Berrick Barnes, 14 Dominic Shipperley, 13 Adam Ashley-Cooper, 12 Pat McCabe, 11 Digby Ioane, 10 Quade Cooper, 9 Nick Phipps, 8 Radike Samo, 7 Michael Hooper, 6 Dave Dennis, 5 Nathan Sharpe (captain), 4 Kane Douglas, 3 Ben Alexander, 2 Tatafu Polota-Nau, 1 Benn Robinson
Replacements: 16 Saia Fainga'a, 17 James Slipper, 18 Scott Higginbotham, 19 Liam Gill, 20 Brett Sheehan, 21 Anthony Fainga'a, 22 Kurtley Beale.
Argentina: 15 Lucas Gonzalez Amorosino, 14 Gonzalo Camacho, 13 Marcelo Bosch, 12 Santiago Fernandez, 11 Horacio Agulla, 10 Juan Martin Hernandez, 9 Martin Landajo, 8 Juan Martin Fernandez Lobbe (captain), 7 Juan Manuel Leguizamon, 6 Julio Farias Cabello, 5 Patricio Albacete, 4 Manuel Carizza, 3 Juan Figallo, 2 Eusebio Guinazu, 1 Rodrigo Roncero.
Replacements: 16 Agustin Creevy, 17 Juan Pablo Orlandi, 18 Leonardo Senatore, 19 Toms Leonardi, 20 Nicolas Vergallo, 21 Martin Rodriguez, 22 Juan Imhoff.
Date: Saturday, September 15
Venue: Skilled Park, Gold Coast
Kick-off: 20.00 AEST; 10.00 GMT
Expected weather: Mostly sunny. 20k/ph south easterly wind. High of 21, low of 12
Referee: Wayne Barnes (England)
Assistant referees: Nigel Owens (Wales), Glen Jackson (New Zealand)
TMO: Matt Goddard (Australia)