The full-back as a pressing trigger

Take the Champions League final in Munich. Real Madrid vs Atletico Madrid, 2016. Watch the early minutes again and ignore the ball. Look at Juanfran on Atletico's right side.

He starts high. Not reckless, but high enough that Real's left winger can pin him. That leaves space behind Juanfran for Marcelo to run into. Real spotted it inside ten minutes. They played two or three balls into that channel before the first goal came from a similar position. One pass into that space, one cutback, goal.

The shape told you before the ball moved. A full-back pushed too high without cover is an invitation. The team that reads it first controls the half-space on that side.

Watch where the full-back stands in the first five minutes. That tells you which passing lane the opposition will try to open.

Question: What is the first positional detail you check when a team sets up in a back four?