Over the next eight days, the Caltex Socceroos face their biggest two matches in the last four years.
Across a minimum of 180 minutes against Honduras - first in San Pedro Sula on November 11 (AEDT) and five days later in Sydney - their World Cup fate will be decided.
So, what's the best way to approach a two-legged tie?
Here are some of the questions both coaches will be considering ahead of the winner-takes-all intercontinental playoff.
AWAY GOALS ARE CRUCIAL
In the event of an aggregate draw across the two legs, the team scoring the most away goals will progress to Russia 2018.
For example, if the first leg is drawn 1-1 and the second leg is a 0-0 draw, Australia would triumph based on scoring more goals away from home than Honduras.
Remember though, this only comes into play in the event of the tie being level after 180 minutes.
Ideally, Australia will be ahead on aggregate and away goals won't matter.
ATTACK OR DEFEND IN GAME ONE?
This is the million-dollar question facing Caltex Socceroos boss Ange Postecoglou.
Does he send his team out looking to score goals in the first game?
Or does he set out his stall a little more cautiously, do everything not to concede and then try to sew things up back in Sydney against a Honduras side that will have little time to prepare once they land in Oz?
Logic would suggest – as outlined above – that scoring goals in Honduras will go a long way towards securing World Cup qualification.
However, Honduras are certain to attack in their home leg as they look to bring an advantage Down Under, which can leave gaps for the Aussie attack to exploit.
Australia’s approach in game one is perhaps the biggest key to the entire playoff and will dictate Ange's selections for Saturday morning.
PLAY UNTIL THE END
Unlike a normal 90-minute game, the first leg is really only the "first half" of the tie.
Any late goals scored could be absolutely pivotal to the end result.
For example, if Australia were 2-0 down in Honduras, but scored late to make it 2-1, they'd only need to win 1-0 at home to win the tie.
You simply must play to the final whistle, especially in the first game, because a goal in such a scenario could be utterly crucial.
A 2-1 loss to the Caltex Socceroos would not be the end of the world.
KEEP THE TIE ALIVE
Whatever happens, the Caltex Socceroos need to board the plane home to Sydney with the tie alive.
A win or a draw in the first game would certainly achieve that.
Even a narrow defeat (say, 1-0) wouldn't be catastrophic; the players would firmly believe they could overturn that deficit with the help of a raucous ANZ Stadium crowd five days later.
After all, against Uruguay in 2005, Australia lost 1-0 in Montevideo, but did the business back home.
But a heavy defeat in San Pedro Sula would leave Australia chasing the return leg rather than being able to dictate terms.
So, a two-legged tie is often a battle of wits, physical preparation and tactics.
When are your Caltex Socceroos in action this weekend?
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