Australia may have lost their World Cup warm-up match to Mexico 1-0. But with just two weeks until their first match of the tournament against Turkey, the Socceroos appear to have found something more important: confidence.

A second-half turnaround against Fifa’s 15th-ranked side almost secured a draw for the Socceroos, who had three good chances to equalise on Saturday night in California. Despite a conservative approach, Tony Popovic’s side showed resilience and increasing positivity as they took the game to the World Cup co-hosts and 78,479 mostly green-clad fans who filled the Rose Bowl Stadium.

The defeat is a reminder, however, there will be little room for error at the World Cup for an Australian side featuring few elite talents. It also heightens pressure on Popovic to get the selection right for his squad, which is due to be announced on Monday.

Against Mexico, there was no first Socceroos appearance for Cristian Volpato after the weekend shock of his switch of allegiance. The late call-up was left out of the squad, alongside forwards Brandon Borrello and Tete Yengi and goalkeeper Joe Gauci, adding intrigue as Popovic prepares to make his final four cuts.

Defender Harry Souttar – who played the entire match – said he didn’t want to celebrate his own selection yet, and it will be cruel on whoever is left out. “There’ll be a few disappointed boys going to miss out on it, which is obviously a tough thing,” he told Paramount+. “It’s a real shame, but that’s football.”

The game showed the importance to the Socceroos of Souttar and Irvine, veterans who had been under injury clouds ahead of the tournament but now look likely to be in the XI.

Alongside Souttar, Popovic delivered a surprise on Sunday in selecting 18-year-old Lucas Herrington – who produced a mostly accomplished performance – on the left side of the back three, rather than the more experienced Cam Burgess. The coach’s decision to deploy the robust duo of Connor Metcalfe and Mathew Leckie in the attacking midfielder roles, leaving Nestory Irankunda on the bench, signalled a cautious approach.

That played out in the first half as Australia consolidated their reputation – fair or not – as defensively minded wreckers. Mexico enjoyed three-quarters of possession early on, but were provided few genuine opportunities. The nature of the breakthrough was, therefore, a surprise and disappointment.

Mexico’s goal came from a corner, a relatively feeble glancing header by Johan Vásquez after Aiden O’Neill couldn’t stretch for the nodded clearance. The ball squirmed through a crowd of bodies towards Mat Ryan’s back post, which it hit then rebounded back across the line. This was no thumping strike, no majestic piece of skill. This was just dismal.

Australia might never be able to play the world’s best off the park through pass and move, or dribbling skill, but there is no reason why they can’t be one of the most robust outfits at set pieces. That goal highlighted how nothing can be taken for granted; how fine the margins will be for the Socceroos in North America.

When the half-time whistle went, it was 11 shots to three; 396 passes to 132. Just four touches for Australia in the Mexico penalty area. Yet they went into the break having also had the half’s best chance.

Alessandro Circati launched a long ball towards right back Jacob Italiano, but a Mexican defensive mixup left striker Mo Touré with an opportunity he should have taken. A half-clearance fell to the striker with the goalkeeper out of position, and the bouncing ball asked him to side foot it into the open goal. It was an act he would do a hundred times a week without trouble in training yet, slightly unbalanced, he hooked his lob to the left of the goal.

But Touré quickly put it behind him in the second half and was central during the Socceroos’ best period. A Souttar header off a set piece fell to his swinging volley. Even if the Touré shot was blocked, the follow-up was hammered back in by Aiden O’Neill and well saved by Mexico’s substitute keeper Guillermo Ochoa. That was Australia’s first shot on target, and they were not done.

Touré became a target on the counter, as early balls into the channels won the Socceroos field position and crucial set pieces. Souttar’s head was the target at the back post, and suddenly a formula for Australian success emerged. Touré and Souttar might have been the bookends for the revival, but they were supported by ambition in midfield, as the yellow shirts were able to progress from defence to attack with confidence.

The best chances of the second half fell to substitutes Ajdin Hrustic and Kai Trewin, each creating one for the other. Both were the result of driving runs into the area in transition. Though neither was a clear one-on-one, they were legitimate openings in a match otherwise lacking and a sign the Socceroos won’t be Group D easy-beats.

Popovic lamented Australia’s struggle to maintain possession under Mexico’s pressure and to convert chances. “The players just need to believe a little bit more,” he said. “You’re not going to get many chances in football. It’s the World Cup you’re preparing for – you don’t give them any chances. They didn’t have a clear chance, but they scored from the corner.”

The Socceroos now travel to their World Cup training base in Oakland, ahead of their final pre-tournament friendly against Switzerland in San Diego next weekend. “Every day now it feels it’s just getting closer, it’s getting more real,” Souttar said. “A disappointing result tonight, but so many positives to take moving forward.”