The World Cup favourites have been floundering in their first outings, with one narrow win between four of them. So how can they improve?
Argentina's problem seems obvious: profligacy. Iceland took an absolute hammering in their 1-1 draw, facing down 27 shots from some of the world's best attackers. Argentina also had 10 corners, 25 crosses, 78 per cent possession and made 751 passes but could not find a second goal.
The biggest culprit was also the side's biggest talisman. Lionel Messi had 11 shots without scoring - including his saved penalty - which was the most taken fruitlessly at a World Cup finals since 1970.
Was he trying too hard, attempting to replicate Ronaldo's impact in Portugal's 3-3 draw with Spain? If so, he needs to detach and relax. The more he tried against Iceland, the more he struggled. Against Croatia on Friday, they cannot be so wasteful.
Brazil had 21 shots taken by 11 players in their draw against Switzerland on Monday, as well as seven corners, but their major concern in attack was the way Neymar was stifled.
The Paris Saint-Germain striker became the most fouled player in a World Cup match in 20 years; of Switzerland's 19 fouls in the game, 10 were on Neymar. Part of the problem stemmed from Neymar taking on too much responsibility. He attempted 11 dribbles but completed just five. He needs more support.
Brazil had negligible territorial advantage over the 90 minutes and less possession in the first half. They lost the ball 124 times - just less than Switzerland's 130.
Casemiro needs to take these games by the scruff of the neck in midfield, as he did for Real Madrid last season. Their next test will come against Costa Rica but Brazil have the talent to unpick their midfield.
Joshua Kimmich was hailed as the best right back in the world after his Euro 2016 performances but in the defeat by Mexico, he had just 18 touches in his own half and spent most of his time bombing forward.
He lost the ball 19 times, the second-most in the team, and did not make a tackle. This irked centre back Mats Hummels, who said: "If seven or eight players attack, then it's clear the offensive force is greater than the defensive stability."
In midfield, the blame was shared. Mesut Ozil won only one of his seven duels and did not make a tackle. Thomas Muller did not muster a shot and had a pass completion rate of 71 per cent. He gave the ball away 22 times. Sami Khedira, taken off after an hour, did not make a tackle and gave the ball away for Mexico's goal.
Germany have plenty of European and World Cup winners but they underperformed badly. Defensive discipline and midfield steel are required in their remaining group games.
France scraped past Australia, relying on the video assistant referee and goal-line technology to win 2-1. The squad has been feted as the most valuable in the tournament, worth £950 million ($1.8 billion), but there are question marks over how Didier Deschamps deployed the front three of Antoine Griezmann, Ousmane Dembele and Kylian Mbappe.
The 4-3-3 formation was unfamiliar - Deschamps had used 4-4-2 in qualifying and 4-3-1-2 in the warm-up friendlies - and it showed.
The heat map for Griezmann, Dembele and Mbappe shows how lopsided France were, with too much emphasis on their left-hand flank.
Dembele did not take a shot in 70 minutes and lost the ball 14 times. Griezmann did not make a tackle and lost it 13 times but did have three shots on target. Mbappe had one.
Peru and Denmark should provide stronger opposition than Australia but, with France's depth and ability, the group stage should still be easily navigated.