Somewhere, Michael Cheika and Wallabies forwards coach Simon Raiwalui were watching – possibly from behind a sofa.

Fainga'a's lineout woes worked their way through the Brumbies' entire system like a poison.

The short passing between their forwards, who had been so good for most of the year, started to fall apart: in the first 50 minutes alone there were three instances of the big men overrunning the ball carrier.

But it all started at the set-piece.

Laissez-faire referee Mike Fraser denied the Brumbies access to the game with his scrum rulings and with the lineout so terribly unreliable the Brumbies were like a tank without any petrol: they looked good but they just couldn't get moving.

Fainga'a's defenders will point out that he has been solid all season and the Brumbies' lineout has been firing at 90 per cent. That's undeniably true, but the regular season simply doesn't carry the pressure of finals footy. In a semi-final, the closest thing Fainga'a has experienced to a Test so far this year, those old demons suddenly appeared.

The loss – or more accurately the nature of it – completes a bad month for Wallabies fans whose mood in recent years naturally veers between hopeful and terrified, and will now lurch towards the latter again.

There is even a quite awful possibility at the upcoming Rugby World Cup that no one wants to speak about: that is, the Wallabies might struggle to emerge from what increasingly looks like a tough old pool.

They are lumped in with Wales, Fiji, Georgia and Uruguay with the top two to progress to the quarter-finals in Japan.

Cheika's side was superb in progressing from a similar group in 2015 – and going all the way to the final – but a lot of water has passed under the bridge since then, much of it choppy, and the fact is that the Wallabies have lost more games than they have won in the four years since the last Rugby World Cup.

For those still in the "that will never happen, look at our Rugby World Cup pedigree" camp, here's a reality check: in World Rugby's rankings system, Fiji (ninth – 77.95 points) are closer to the Wallabies (sixth – 82.40 points) than Australia are to Ireland (third – 88.69 points).

Fiji are clearly the danger side in the Wallabies' group because they beat France at the end of last year, and will have plenty of talent to choose from, including Semi Radradra and Leone Nakarawa.

​The Fijians have also organised two high-quality fixtures against the New Zealand Maori in July as they ramp up their preparations, so there is a real sense of purpose about their campaign.

Let's not throw Fainga'a to the wolves.

He has had another strong campaign and although the quality of his work might have been exaggerated by his try-scoring stats from rolling mauls, his all-round play is superior to the rising Alex Mafi, while Brandon Paenga-Amosa appeared to fall out of favour at the Reds and the Rebels' Jordan Uelese only returned late in the campaign.

Also, other Brumbies forwards failed to fire against the Jaguares as the occasion and/or travel appeared to have an effect.

But, make no mistake, the root cause of so many Wallabies ills last year was the lineout and if they don't sort that out they will be Rugby World Cup quarter-finalists at best.

And guess who Fainga'a could run into in that last-eight game? The same Argentine forwards who caused him so much grief on Saturday.