Total Football (Dutch: totaalvoetbal) is the label given to an influential tactical theory of football in which any outfield player can take over the role of any other player in a team. It was pioneered by Dutch football club Ajax from 1965 to 1973, and further used by the Netherlands National Football Team in the 1974 FIFA World Cup. It was invented by Rinus Michels, who was the coach of both Ajax and the Netherlands national team at the time. In Total Football, a player who moves out of his position is replaced by another from his team, thus retaining the team's intended organisational structure. In this fluid system, no outfield player is fixed in a nominal role; anyone can successively play an attacker, a midfielder and a defender. The only player fixed in a nominal position is the goalkeeper. Total Football's tactical success depends largely on the adaptability of each footballer within the team, in particular the ability to quickly switch positions depending on the on-field situation. The theory requires players to be comfortable in multiple positions; hence, it places high technical and physical demands on them. During this era Ajax played some of their finest football ever, achieving home wins (46–0–0) for two full seasons (1971–72 and 1972–73), just one defeat in the whole of the 1971–72 season, and celebrating five titles in 1972 (the Netherlands national league, KNVB Cup, European Cup, European Super Cup and Intercontinental Cup).