The Wallabies rallied in the wet for a 20-19 comeback win against Argentina in a soaked La Plata thanks to a Ben Donaldson penalty kick on the siren.
Ben Donaldson kicked a penalty from right in front after the siren to claim the win in a dogged affair.
Argentina started fast to take a 10-0 lead but the Wallabies were in the fight when Jake Gordon dived under the points.
Rob Valetini's try put them in front in the middle of the second half but Argentina looked to have celebrated Agustin Creevy's last game in style when they kicked a late penalty.
The Wallabies kept pressing and got the perfect opportunity when Argentina infringed right in front of the posts with seconds left.
It allowed Donaldson to kick the three to secure their first win of the Rugby Championship
The conditions dictated the contest as a steady downpour of rain before and during the match left players from either side struggling for handling.
The Australians built pressure early with 27 phases of attack but it was Argentina that struck first through the boot of Santiago Carreras.
A penalty on the Wallabies line offered the hosts a chance to extend their lead and number eight Juan Martin Gonzalez powered over via the rolling maul.
Trailing 10-0, the Wallabies remained patient in defence and responded through Jake Gordon.
Some great interchange from Len Ikitau and Tom Wright opened the space for the scrum half, who dived under the posts after a Wright offload.
Argentina added three more points before the break for a 13-7 lead, with the Aussies missing a chance late to reduce the margin.
The hosts added three more points to start the second half before the Wallabies unleaded a picture-perfect team try.
It started when Ikitau beat a pair of defenders to break through before some brutal runs set up Rob Valetini to crash over the line to reduce the lead to two points.
The boot of Lolesio put Australia in front for the first time in the match but their inability to handle a restart hurt them again.
It put Argentina straight back on the attack, with only a desperate try saving tackle from Harry Wilson stopping Thomas Gallo at the line.
The hosts took their chance to re-take the lead via the boot of replacement Tomas Albornoz.
It failed to dent the Wallabies' confidence and they pressed for a winner.
Lolesio broke the line with six minutes to go but couldn’t find Max Jorgensen on the 22.
This allowed the Wallabies to press the line as inch by inch they wore down Argentina.
As the desperation started to seep in, Schmidt’s side forced the infringement from replacement Mayco Vivas right in front of the posts as he went through the ruck illegally trying to force a mistake from Angus Bell.
It allowed Donaldson to wind down the clock and slot the easiest of three points for a crucial victory.
“(I’m) really proud,” coach Joe Schmidt said post-match.
“We made a few things hard for ourselves, giving them a head start at home with a loud crowd and in very difficult conditions with a swirly wind and a very breezy ball, but we didn't control the kickoff well and often put ourselves straight back under pressure, which was frustrating.
“But we built our way forward, scored a couple of good tries and created a couple of other chances that it would have been great to give us a little bit of maybe breathing space or put us into the contest on a positive footing.
“We have a lot of work to do but we’re pleased to get the four points and we’re in the contest."
Scorers:
Argentina: Try: Juan Martin Gonzalez. Coversion: Satiago Carreras. Penalties: Santiago Carreras (3), Tomas Albornoz
Australia: Tries: Jake Gordon, Rob Valetini. Conversions: Noah Lolesio (2). Penalties: Noah Lolesio, Ben Donaldson.
Argentina: 15 Juan Cruz Mallia, 14 Santiago Cordero, 13 Lucio Cinti, 12 Santiago Chocobares, 11 Mateo Carreras, 10 Santiago Carreras, 9 Gonzalo Bertranou, 8 Juan Martin Gonzalez, 7 Marcos Kremer, 6 Pablo Matera, 5 Pedro Rubiolo, 4 Franco Molina, 3 Joel Sclavi, 2 Julian Montoya (captain),1 Thomas Gallo. Replacements: 16 Agustin Creevy, 17 Mayco Vivas, 18 Eduardo Bello, 19 Guido Petti, 20 Tomas Lavanini, 21 Santiago Grondona, 22 Lautaro Bazan Velez, 23 Tomas Albornoz.
Australia: 15 Tom Wright, 14 Andrew Kellaway, 13 Len Ikitau, 12 Hamish Stewart, 11 Marika Koroibete, 10 Noah Lolesio, 9 Jake Gordon, 8 Harry Wilson, 7 Carlo Tizzano, 6 Rob Valetini, 5 Lukhan Salakaia-Loto, 4 Nick Frost, 3 Taniela Tupou, 2 Matt Faessler, 1 Angus Bell. Replacements: 16 Josh Nasser, 17 Isaac Kailea, 18 Allan Alaalatoa, 19 Jeremy Williams, 20 Langi Gleeson, 21 Tate McDermott, 22 Ben Donaldson, 23 Max Jorgensen.