The Wallabies won just four of 13 games last year - their worst campaign in decades - and after a 35-17 loss in the Rugby Championship opener against South Africa in Johannesburg last weekend the pressure is on again.
Despite two disallowed tries last week, the Wallabies had chances to stay in the hunt but failed to convert them, something Cheika wants to see fixed.
"Making opportunities isn't good enough, taking them is what it's about," he said.
"We've just got to understand the momentum of the game, when we've got the flow and it's happening to have a real go at it... show our hand.
"That's probably the thing we need to work on the most... and translate those opportunities into points."
Cheika has just four more opportunities to nail down his best combination ahead of the World Cup in Japan later this year, starting with Mario Ledesma's fast-improving Pumas in Brisbane.
He has picked a new-look backline, with cancer-survivor Christian Lealiifano starting his first Test in three years at fly-half.
The Brumbies skipper replaces Bernard Foley alongside scrumhalf Will Genia, winger Marika Koroibete and Kurtley Beale at fullback, with Nic White, Tom Banks and Dane Haylett-Petty missing out.
Prop Scott Sio returns from a hamstring injury to replace James Slipper.
"What's important about a World Cup is having a squad that you can have injuries, games where you need to rotate, to have players or groups of players that can come in at different times is critical for us," skipper Michael Hooper said.
"Guys have moved into starting positions this week and it's been pretty seamless."
Genia will be playing his last Test in Brisbane before retiring from international duty after the World Cup, while bad boy utility back James O'Connor is set to make his first appearance in six years, off the bench, since having his contract ripped up for misbehaviour.
Argentina, who agonisingly lost to the All Blacks 20-16 in Buenos Aires last weekend, have also made five changes to their run-on side with veteran hooker Agustin Creevy omitted due to injury.
Argentina coach Mario Ledesma (L) will hope to upset the Wallabies in Brisbane after last week's agonising loss to the All Blacks
He is replaced by Julian Montoya with Toulon backrower Facundo Isa at number eight instead of Javier Ortega Desio while Tomas Lezana plays at blindside flanker.
Santiago Cordero comes in at right wing for Matias Moroni, who shifts to outside centre with Matias Orlando dropping to the bench. Joaquin Tuculet will start at fullback ahead of Emiliano Boffelli.
Most of the Pumas play for Super Rugby club Jaguares and are coming off their best-ever season, making the final. That quality was on show against New Zealand where they were desperately unlucky not to win after sustained late pressure.
Ledesma, a former forwards coach with Australia, said there were a lot of positives going forward.
"It was disappointing last weekend, we could have won. Obviously those four points is not a big difference, but it means we still have work to do to win those kind of games," he said this week, pointing to neutralising Australia's pack as key in Brisbane.
"The Wallabies I think are playing a more direct style of rugby, especially because they have very big guys... so it will be a challenge to stop their momentum."
Australia have lost just of one their last eight games against Argentina - on home soil last year.
Kick-off is at 11:45 SA time.
15 Kurtley Beale, 14 Reece Hodge, 13 Tevita Kuridrani, 12 Samu Kerevi, 11 Marika Koroibete, 10 Bernard Foley, 9 Nic White, 8 Isi Naisarani, 7 Michael Hooper (captain), 6 Lukhan Salakai-Loto, 5 Rory Arnold, 4 Izack Rodda, 3 Sekope Kepu, 2 Folau Fainga’a, 1 Scott Sio.
Substitutes: 16 Tolu Latu, 17 James Slipper, 18 Taniela Tupou, 19 Rob Simmons, 20 Luke Jones, 21 Nic White, 22 Matt Toomua, 23 James O’Connor
15 Joaquin Tuculet, 14 Santiago Cordero, 13 Matias Moroni, 12 Jeronimo de la Fuente, 11 Ramiro Moyano, 10 Nicolas Sanchez, 9 Tomas Cubelli, 8 Facundo Isa, 7 Tomas Lezana, 6 Pablo Matera (captain), 5 Tomas Lavanini, 4 Guido Petti, 3 Juan Figallo, 2 Julian Montoya, 1 Nahuel Tetaz Chaparro
Substitutes: 16 Santiago Socino, 17 Mayco Vivas, 18 Ramiro Herrera, 19 Matias Alemanno, 20 Juan Manuel Leguizamon, 21 Felipe Ezcurra, 22 Joaquin Diaz Bonilla, 23 Matias Orlando