The increasingly fanciful hope in Argentina was that this World Cup would bring Lionel Messi’s career peak, but the deepening worry around the squad is that it has already brought one of his worst lows in the game. They’ve never really seen him like this, as withdrawn and sombre as he has been in their Bronnitsy base over the last few days.

Saturday’s penalty miss against Iceland has hit him hard. The 30-year-old could barely show his face the next day. Although the Argentine staff had organised a family barbecue to celebrate father’s day, Messi didn’t go. He stayed in the room he shares with Sergio Aguero, alone.

It should be noted Messi’s own family were not there, as they don’t arrive until the next few days, so that will have increased his desire to stay away – but it was just as noteworthy that his wife Antonella felt the need for a public show of support on Instagram.

Argentina vs Iceland - player ratings Show all 22 1 /22 Argentina vs Iceland - player ratings Argentina vs Iceland - player ratings Willy Caballero 5/10 Did not look particularly comfortable at any stage of the game and like the rest of the defence a bit haphazard at times - susceptible for the first goal. Getty Images Argentina vs Iceland - player ratings Eduardo Salvio 6/10 A rather uninspiring performance - not much to say either negatively or positively. AFP/Getty Images Argentina vs Iceland - player ratings Nicolas Otamendi 6/10 A strong presence but has also got a mistake and chaotic decision in him. Getty Images Argentina vs Iceland - player ratings Marcos Rojo 5/10 Doesn’t appear to be at full fitness. Hasn’t been in the first team at Manchester United for most of the season and it showed with Finnbogason running him ragged. Did, inadvertently, set up Argentina’s only goal, mind. Getty Images Argentina vs Iceland - player ratings Nicolas Tagliafico 6/10 A very reasonable display and looked okay going forward with a cleverly flicked header. AFP/Getty Images Argentina vs Iceland - player ratings Javier Mascherano 7/10 Showed a good range of passing but a bit leggy. AFP/Getty Images Argentina vs Iceland - player ratings Lucas Biglia 7/10 Looked good in stages, had a couple of threatening moments and linked up the play nicely. Getty Images Argentina vs Iceland - player ratings Maximiliano Meza 6/10 A few histrionic moments but a relatively decent performance in general and made the run for the penalty. Getty Images Argentina vs Iceland - player ratings Lionel Messi 6/10 Not the main man today, but good at what he did. Always looks a threat and tested the keeper enough times BUT, importantly, missed the golden opportunity provided to him with another penalty miss. AFP/Getty Images Argentina vs Iceland - player ratings Angel Di Maria 5/10 Looked good in stages, had a couple of threatening moments and linked up the play nicely. AFP/Getty Images Argentina vs Iceland - player ratings Sergio Aguero 8/10 Fabulous play for the opening goal to give himself the space. General play was reasonable but doesn’t matter when you can produce moments of magic. Getty Images Argentina vs Iceland - player ratings Hannes Þór Halldórsson 9/10 Strong and decisive (unlike his opposite number), making saves when called upon and saved the penalty from Messi. Getty Images Argentina vs Iceland - player ratings Birkir Már Sævarsson 7/10 A good and competent display, part of an organised unit. AFP/Getty Images Argentina vs Iceland - player ratings Kári Árnason 7/10 A key figure in iceland’s defence looked at ease defending against some of the world’s best talent. AFP/Getty Images Argentina vs Iceland - player ratings Ragnar Sigurðsson 8/10 Crucial interceptions and a threat going forwards as well. Can be proud of his performance. Getty Argentina vs Iceland - player ratings Hörður Björgvin Magnússon 6/10 A steady if unspectacular game but a big part of Iceland’s defensive block in general. AFP/Getty Images Argentina vs Iceland - player ratings JB Gudmundsson 7/10 Played a big part for Burnley this year in helping them qualify for Europa League and was equally instrumental today before his injury on the hour mark. AFP/Getty Images Argentina vs Iceland - player ratings Aron Gunnarsson 6/10 Not his best game, but not bad. Maybe we can blame the ref for standing on his heel. Still led the team with vigour. AFP/Getty Images Argentina vs Iceland - player ratings Emil Hallfreðsson 7/10 Strong performance in general and some threatening long-throws. AFP/Getty Images Argentina vs Iceland - player ratings Birkir Bjarnason 6/10 The Aston Villa man who opened Iceland’s account at Euro 2016 squandered the chance to do so here but a generally good performance. Getty Images Argentina vs Iceland - player ratings Gylfi Sigurðsson 8/10 Iceland’s best known player didn’t let down his team today, creating chances and showed Iceland’s coolness on the ball. AFP/Getty Images Argentina vs Iceland - player ratings Alfreð Finnbogason 9/10 Led the line like a true number 9 (despite being a no.11) but scored the goal and looked a menace throughout. AFP/Getty Images

This is a man who feels he’s let his nation down. “I am responsible for what happened,” Messi said after Iceland, and he fears for what could happen next. He’s all too aware of the stakes at this World Cup, for both himself and Argentina.

Many around the Argentina camp have picked up on how often he said some variation of “it’s now or never” to media in the build-up to this World Cup. All he can seem to see right now is “never”.

For their part, the rest of the Argentine squad have themselves been highly aware of Messi’s downbeat mood, and the need to lift him in more ways than one. They fully recognise they are effectively here because of him, that his talent represents their only chance of going far, but that it’s unfair to always expect him “to be Superman”. They want to work out a system that is best for Messi, and offer support in so many ways. They want to step up.

It’s just that Messi is so fundamentally important to Argentina that if he isn’t right, it can disrupt the rhythm of the whole side. And this is a group that, according to those close to the camp, don’t deal with setbacks well.

It’s for that reason manager Jorge Sampaoli has been so focused on mental work in the build-up to this huge match against Croatia. There’s been a lot of talk about sports psychology around their Bronnitsy base, but the deeper and typical problem for Argentina is that they just can’t afford to focus on that. They have so much work to do.

It’s not just that Croatia have a better system, but that they have one that works, in a way that Argentina’s does not. That has meant Zlatko Djalic’s side also have something else Argentina do not: belief, confidence.

Lionel Messi has withdrawn from his Argentina teammates after the penalty miss (Getty Images)

“We have phenomenal players, from the goalkeeper to the defenders to the attackers,” Mateo Kovacic declared on Tuesday. “We don’t need to fear Argentina. We believe we are better than they are.”

That probably isn’t even hubristic bravado either, but rather a fair assessment of reality. A mere glance at the Argentina line-up against Iceland re-affirms. There are some big names, but then a lot of little-known names, because of what is a front-loaded squad. And if Argentina are missing key pieces, this game looks like it’s falling into place to provide one of those jarring reality checks, the kind of hard reckoning when it all caves in. The real end of an era. Indeed, it’s difficult to know how they’re going to get the ball off Croatia, given the quality of Luka Modric and Ivan Rakitic in midfield.

Argentina just can’t touch that quality, and may not be able to get near them without a serious reshaping of the side. Just one other factor worsening Messi’s mood is reportedly his sense of responsibility for suggesting the midfield pair of Javier Mascherano and Lucas Biglia, a pairing that simply didn’t work against Iceland.

With so much doubt and hesitation, Sampaoli has attempted to offer a certain decisiveness of his own. He is making big changes to the team. Sampaoli is first of all throwing out the four-man backline the players say they prefer, and returning to his own idealised three. He is then jettisoning three of the old guard in Angel Di Maria, Marcos Rojo and Biglia, and bringing in younger players in Nicolas Tagliafico, Cristian Pavon and Marcos Acuna.

The message around the Argentina camp over the last few days is that, against Croatia’s possession, they are ‘going to have to run… and run and run’ (REUTERS)

These are more of the lesser-known names, but the entire point is that they are pumped to make a name for themselves – and make the drives Sampaoli’s football requires. It’s something he particularly wants for this game.

The message around the Argentina camp over the last few days is that, against Croatia’s possession, they are “going to have to run… and run and run”.

Given even the dysfunctional last few games of qualification and the squad’s disrupted preparation programme, this feels a real risk. It may further precipitate that cave-in.

But it may also be the jolt they badly need, the big difference to cause the big change in mood and get them thinking about something else.

The bottom line, though, is that if Messi in any way turns it on, he can still turn everything on its head.

Messi’s ability to produce something out of nothing could still see Argentina rally at this World Cup (Getty Images)

Sampaoli’s changes might help that but, even then, Messi’s mood should not be dwelt upon as a negative even if he is far from feeling positive.

His history suggests that sombre demeanour and solitude are not the set-up for worse, but the prelude to something better. In the past, he has often similarly retreated, but only to consider everything so he can get himself primed and ready. Many in the Argentina squad saw the same thing after a frustrating first game of the 2015 Copa America.

One source very familiar with the Barcelona set-up meanwhile told The Independent: “Messi will turn up. I’m sure about it.”

That’s what they’ve known of him, that’s what they fully expect from him. That’s why it all still comes back to him: the squad’s mood, the match, the group and maybe still the World Cup.