To progress to the semi-finals, the Socceroos must defeat the South American champions, but even that might not be enough.                                           

While Ange Postecoglou’s side are insistent that they remain focused on the present tournament, the clash with Chile will also be the team’s final game before a decisive qualifier away to Japan.

If a heavy defeat dents morale ahead of the Japan trip, Australia might not be returned to Russia next year.

Here are five things to watch at the Spartak Stadium.

1. Who will face Chile?

Ahead of his team’s third match in seven days, Postecoglou was up-front about the likelihood of changes to his starting line-up.

“Everyone is fit but we will have a check of fatigue levels,” the coach said. “The last game took a fair bit out of us considering we had a day less rest. Recovering has been very good though, the boys have been diligent.

“We will make some changes tomorrow – I will have a look at them today, give them another 24 hours to recover and then I will make the decisions.”

Will Massimo Luongo get another start?

Following his star performance against Cameroon, defender Alex Gersbach – the youngest player in the Socceroos’ squad – is likely to be rewarded with another start.

In the midfield, Postecoglou faces a real dilemma. When on-form, Aaron Mooy and Tom Rogic are two of Australia’s best players.

But Mooy looks fatigued after a lengthy season in the English Championship, while Rogic has a history of injuries.

Does Postecoglou risk both in this crunch match? Or give Massimo Luongo another chance?

Similar uncertainty surrounds the three-man defence. Bailey Wright, Trent Sainsbury and Milos Degenek have all played 180 minutes in the tournament to date, and their weariness is compounded by Australia’s intense travel schedule.

 

2. The maths

No team in Group B has yet qualified for the semi-finals. Chile and Germany have four points each, while Australia and Cameroon are both on one point.

To ensure progression, the Socceroos must beat Chile by two goals or more. Three points will take them level with La Roja, while the two goal advantage is necessary for Australia to leapfrog Chile on goal difference.

Can the Socceroos blunt the attack of Chile hitman Alexis Sanchez?

If Postecoglou’s side can only manage a one goal margin of victory, the Socceroos would be reliant on Cameroon beating Germany by a single goal and scoring less goals than Australia.

That would leave all four sides level on four points, with Australia holding the joint second-best goal difference in the group with Germany.

Goals scored would then be the deciding criterion – the Socceroos have scored three to the world champions’ four, such that a 2-1 victory over Chile and a 1-0 win to Cameroon would earn Australia a semi-final spot.

If both sides score an equal number of goals, head-to-head record acts as the tie-breaker. In those circumstances, Australia’s opening loss to Germany would send them home.

3. A century for Cahill

If Tim Cahill starts or is substituted on against Chile, it will mark his 100th appearance in Australian colours.

Much has been said about Cahill’s achievements, and he will be remembered as one of this country’s greatest ever footballers.

Can Timmy rise above the pack one more time?

Not that the former Everton star will let this milestone influence his performance. “When I am on the pitch it is all business,” Cahill said on Saturday.

The 37-year-old has had little impact at the Confederations Cup, coming on as a late substitute in each match.

Against Chile, though, Cahill’s aerial ability could be crucial.  The South Americans’ defensive unit is short in stature, and they conceded to Russia from a header in a pre-tournament friendly.

Can Cahill do it one last time for the Socceroos?

 

4. Closing out the period before half time

Against Cameroon, the Socceroos conceded moments after the fourth official signalled one minute of injury time prior to the break.

In the defeat to Germany, Australia gave away a penalty in the 44th minute, which Julian Draxler had no difficulties converting.

And when the national team played Saudi Arabia at home prior to the Confederations Cup, the visitors found the net with seconds left in first half.

Can the Aussie defence hold firm?

Against Germany and Cameroon, the ultimate outcome might have been different had the opposition not scored at such a vital time.

If Australia is going to beat Chile by two goals, they simply cannot afford to concede another goal on the half time whistle.

5. Postecoglou’s record

There is no doubt that the Australian manager’s time with the national team has been successful. Lest we forget that the Socceroos won the 2015 Asian Cup, perhaps the side’s biggest ever triumph.

Yet at FIFA tournaments – the 2014 World Cup and now in Russia – Postecoglou has struggled.

Admittedly neither group was favourable – Spain, Chile and Holland in Brazil and now Germany, Cameroon and Chile at the Confederations Cup.

What will be Postecoglou's legacy from the Confeds Cup?

But a manager’s job is to get results, and Australia has earned just a solitary point in these five games.

Unless Australia beat Chile, Postecoglou’s disappointing run in FIFA competitions will continue.

Given the Socceroos’ qualification for the 2018 World Cup is far from assured, that record could become an unglamorous part of his legacy.