Why did great teams stop marking men and start marking space?

For decades the standard way to defend was simple: give every defender an opponent and follow him. Man-to-man marking assigns each defender a specific opposition player. Zonal marking does the opposite: a defender covers an area of the pitch, marks any opponent who enters it, and hands the man over to a teammate when he leaves.

Man-marking had its heroes: Berti Vogts on Johan Cruyff in 1974, Claudio Gentile on Diego Maradona and Zico in 1982, Guido Buchwald on Maradona in 1990. But tight man-marking was often at the expense of attacking spectacle, because defenders preoccupied with their markings may be reluctant to join the attack. Zonal marking's biggest advantage is flexibility: when the team wins the ball, players are still in their positions and can start an attack more quickly. It is hard at set pieces, where most teams change to man marking, but overall it won the argument: 15 of the 16 teams that reached the knockout stages of the 2004 Champions League used zonal marking.

One man pushed it in Italy, the home of catenaccio, and he had never been a professional player. Arrigo Sacchi worked for years as a shoe salesman. When critics doubted him, he said he never realised that to become a jockey you have to have been a horse first. His Milan played an attacking 4–4–2, discarded the libero, and used zonal marking, which his predecessor Nils Liedholm had already introduced, with a high press and the offside trap that Sacchi is credited with popularising. They won two back-to-back European Cups.