The Wallabies have been unable to back up their opening Rugby Championship success, crashing to a 48-17 loss to Argentina in a helter-skelter affair in San Juan.

It was the Pumas’ biggest-ever win over the Australians and, on the back of the thumping bonus-point victory, they moved to the top of the four-nation standings.

Argentina raced to a 26-10 half-time lead with the Wallabies unable to repeat the second half surge that led to their Mendoza Test win last week.

Australia had a James O’Connor try, which would have given them the lead, disallowed in the 20th minute in a baffling refereeing decision and the Pumas scored minutes later for a 14-point swing.

It proved a turning point with the remainder of the game almost one-way traffic in a disappointing display by the visitors.

“Massive disappointment. It’s not good enough,” Wallabies coach Dave Rennie said. “We conceded four tries with kicks in behind us and certainly got dominated in the collision area and created plenty of opportunities but we’ve got to be patient. A ruck’s not a disaster; just not clinical enough.

“We had a good enough side on the paddock to do the job,” said Rennie. “We gave them a few soft points early on, fought our way back into it. We’ve got to be better and while we’ll get a few guys back, whoever puts the jersey on has to front and we weren’t good enough.

“We certainly want to earn the respect of the country and you don’t do it with performances like that.”

Rennie will return to Australia feeling out-coached after Pumas coach Michael Cheika switched up his gameplan and used Argentina’s contestable kicking game to expose the inexperience of Australia’s back three.

The home side piled on the pressure in a physical performance with the Wallabies, who are missing key men such as skipper Michael Hooper through personal leave and injury, bereft of answers.

Australia got off to the worst possible start and they trailed 14-0 after seven minutes. Veteran winger Juan Imhoff opened the scoring in the first minute when he pounced on a mix-up between Wallabies winger Jordan Petaia and full-back Tom Wright and raced to the line.

On the back of a 50-22 kick by Santiago Carreras the Pumas had an attacking lineout five metres out with fired-up prop Thomas Gallo barrelling over.

The Wallabies started to find their feet and got on the board in the 12th minute after Rob Valetini charged ahead and set up a quick pick and go for skipper James Slipper to score, which was soon backed up by an O’Connor penalty for a 14-10 scoreline.

It looked like the visitors would take the lead after O’Connor crossed after some clever interplay with Petaia but referee Karl Dickson and the TMO deemed an earlier clean-out by Slipper was illegal.

It proved a double blow when Argentina centre Jeronimo de la Fuente scored down the other end with Emiliano Boffelli adding the extras for a 21-10 lead.

The Pumas again jumped on some box kick confusion from the visitors with flanker Juan Martin Gonzalez this time gifted the ball to touch down.

The half-time margin could have been more ugly but for a miracle try-saving tackle by Marika Koroibete.

The Wallabies were unable to build into the second half through errors and poor decision-making while the hungry Pumas marched on. Gallo grabbed his second and then Boffelli crossed before a try by Tomas Albornoz after full-time capped a memorable match for the home side.

The 31-point loss was the Wallabies’ heaviest against Argentina, surpassing a 15-point margin in 1983.

The shattered Wallabies captain James Slipper, deputising for longtime leader Michael who flew home from the tour last week citing his “mindset”, cut a desolate figure at the end of the record defeat.

“Clearly disappointed,” said Slipper. “Off the back of a good performance last week we wanted to back it up. Probably fell short of standards today. They got the momentum and the crowd behind them and they’re a tough team to play catch up football against. I think we’re excited to get home. It’s been a really tough tour for us.”

With Los Pumas’ victory, and South Africa’s 23-35 defeat by New Zealand earlier in the day, all teams in the Rugby Championship have one win from two matches.