Milan's wing-back positions are the area of the squad that still needs the most work as Ruben Amorim's second week at Milanello gets underway.
The whole project now hangs on a shape Milan haven't used before. Amorim's 3-4-2-1 lives and dies by its wing-backs, the players who have to defend a full flank and attack it in the same breath. Get them wrong and the system collapses into a back five that never gets forward. That is why the flanks, not the centre-backs or the front three, are where the mercato is likely to be decided.
The right side is the crowded one. Alexis Saelemaekers spent much of last season as the starter there, and the question is whether Amorim wants him as a wide defender or pushed up as one of the two attacking midfielders behind the striker. Zachary Athekame is the more natural wing-back of the group and finished last season on an upward curve. The two real unknowns are the players back from loan, Yunus Musah and Samuel Chukwueze.
Interestingly, Amorim has been trying Chukwueze at right wing-back rather than in the number ten area many expected. It looks odd for a player signed as a winger, but it fits the manager's history. At Sporting he turned Geovany Quenda into a wing-back, and at United he did the same with Amad Diallo, converting attacking wide players into two-way flank men rather than buying specialists. The Celtic friendly in Glasgow on Saturday is the next test of that idea, and if it convinces, Milan may not need to spend on the right at all.
The left is where the depth runs thin, and it all revolves around Pervis Estupiñán. Aston Villa are pushing hard, and according to the report the winger has already agreed personal terms with the Ecuadorian, with only the fee between the two clubs still to be settled. Estupiñán is due back at Milanello on July 24, and the suggestion is that Amorim wants to see him in the system before signing off on any sale.
If he goes, the cupboard is close to bare. Davide Bartesaghi is the only other recognised left-back, and while he started last season brightly he faded down the stretch. Amorim could reinvent him as a left-sided centre-back, a role he handled well during his season with Milan Futuro, but that would leave the wing-back spot itself empty.
The fan's question is simple: does this mean a signing is coming? On the left, almost certainly, if Estupiñán is sold. Milan would be down to Bartesaghi and improvisation, and no manager builds a debut season on that. The right can wait on what Chukwueze shows in Scotland. The left cannot wait on anything.