The space behind the full-back ⚽

Watch the first ten minutes of Milan vs Lecce from Sunday. Milan lined up with Chukwueze high on the right and Estupinan pushed forward on the left. That left Gila and Pavlovic alone against Lecce's front three.

The passing lane into the channel disappeared for Lecce, but only because Milan's midfield dropped quickly to cover. Rabiot and Modric sat deep. The shape stayed compact.

When Milan won the ball, the space appeared in the half-space between Lecce's left-back and centre-back. Pulisic drifted there twice before the goal. That is the read: the full-back steps up, the winger moves inside, and the centre-back must choose.

Look at where the full-back stands, not where the ball goes.

Question: When a full-back pushes high, who is responsible for the space behind him in your view?