It’s do or die.
The equation for the Socceroos is simple: beat Peru and score as many goals as possible.
The rest is in the hands of the football gods, with Australia also needing Denmark to lose (against France) and finish match-day 3 with an inferior goal difference to the Socceroos.
If those three elements align, the national team will progress to the round of 16, where a clash with Croatia in Nizhny Novgorod awaits.
If not, the Australians will have a long trip home after crashing out of the World Cup group stage for the third consecutive tournament.
Ahead of the vital clash (broadcast live on SBS), here is what to look out for in Sochi.
1. Who begins up front?
Tomi Juric. Tim Cahill. Jamie Maclaren.
Those are Bert van Marwijk’s choices for starting striker against Peru, following Andrew Nabbout’s tournament-ending injury (unless – as the forward himself suggested – he can pull off a miraculous recovery).
Juric is the obvious option, as a relatively like-for-like replacement who has been coming off the bench.
That, certainly, was the view of a van Marwijk confidant Martijn Krabbendam, who told TWG: “Bert won’t feel it’s appropriate that the vacancy will pass through Juric straight to Cahill.”
Cahill is the enigma.
Australia’s second most-capped player has a vocal lobby calling for his inclusion, but van Marwijk seemed unswayed.
At 38 and with minimal club minutes under his belt this season, Cahill’s ability to make a difference has been questioned.
Finally, Maclaren was a late addition to the Socceroos’ squad and seems unlikely to warrant a starting spot, although with his strong recent club form a substitute appearance is not impossible.
2. Same, same or different?
While Nabbout’s injury necessitates change, the Australian squad is otherwise fit.
That leaves van Marwijk with a dilemma.
He can either keep his faith in the remainder of the starting XI, who have performed well in tough encounters with France and Denmark but failed to score from open play.
Or he can shuffle the deck more substantively, particularly with an eye to fatigue concerns in light of the demanding playing schedule.
If Australia do progress to the round of 16, their next clash would be scheduled for 1 July – five days after the Peru match-up.
While it might be premature to think ahead to the knock-out round, van Marwijk does need to manage his player’s fitness with all eventualities in mind.
3. Are Peru deflated or elated?
The arrival of La Blanquirroja (the white and red) in Russia heralded Peru’s first World Cup appearance since 1982.
Their fans have flocked to the tournament in huge numbers, with some reportedly selling property back home to finance the intercontinental adventure.
While Peruvian supporters may have been unstoppable, on the pitch their national team has slumped to two consecutive defeats.
With Peru’s World Cup already over, are they demoralised – an easy-beat for the Socceroos?
Or is the Paolo Guerrero-led side desperate to restore some pride, such that they will come out firing with nothing to lose?
4. Does Robbie Kruse start?
The curious case of Robbie Kruse.
Following a poor showing against Denmark, Kruse’s performance was roundly criticised.
The ABC gave him a rating of four; FourFourTwo went with 4.5.
Then, the criticism turned ugly.
The Bochum winger has reportedly been subject to death threats and other vile comments on social media.
Over the weekend, Socceroos team-mates came out in support of Kruse.
Personal abuse has no place in the game, and those spouting it have rightly been condemned by a range of stakeholders.
But the fact stands: Kruse struggled against Denmark.
On numerous occasions his first-touch let the team down, while replacement Daniel Arzani was electric.
All of which leaves van Marwijk in a difficult place.
If he benches Kruse, it might be seen as validating some of the abuse and would no doubt have a negative psychological impact on the player.
But if he keeps his faith in the winger, Australia may again fail to generate attacking momentum on the flank.
5. Surreal Sochi
Fisht Stadium, the host of Australia’s must-win clash, is an intriguing place.
Located in Adler, 35 kilometres from Sochi itself, the stadium played host to the 2014 Winter Olympics – making it only the second venue after Italy’s Stadio Olimpico to hold both World Cup fixtures and Winter Olympic events.
The stadium’s sleek design is intended to mirror the jagged peaks of the Caucasus mountains, visible from the stadium, while the gentle waters of the Black Sea lap just a few hundred metres away.
The surrounding Olympic park is similarly exotic – a garish purple roller-coaster, a castle-themed hotel, a giant indoor ice rink (home of local hockey team) and the Russian Grand Prix’s Formula 1 circuit.
The Socceroos have played in Sochi before, beginning their 2017 Confederations Cup campaign here with a 3-2 loss to Germany.
They will be hoping this unusual venue brings happier memories this time around.