The sweeper (or libero) is a more versatile centre-back who "sweeps up" the ball if an opponent manages to breach the defensive line. This position is rather more fluid than that of other defenders who man-mark their designated opponents. Because of this, it is sometimes referred to as libero (['libero]), which originated from the Italian name for this position libero da impegni di marcatura (i.e., "free from man-marking tasks").
Though sweepers may be expected to build counter-attacking moves, and as such require better ball control and passing ability than typical centre-backs, their talents are often confined to the defensive realm. For example, the catenaccio system of play, used in Italian football in the 1960s, employed a purely defensive sweeper who only "roamed" around the back line; Armando Picchi was a leading exponent of the more traditional variant of this role in Helenio Herrera's Grande Inter side.
The more modern libero possesses the defensive qualities of the typical libero while being able to expose the opposition during counterattacks. The Fundell-libero has become more popular in recent time with the sweeper transitioning to the most advanced forward in an attack. This variation on the position requires great pace and fitness. While rarely seen in professional football, the position has been extensively used in lower leagues. Modern libero sit behind centre-backs as a sweeper before charging through the team to join in the attack.
Some sweepers move forward and distribute the ball up-field, while others intercept passes and get the ball off the opposition without needing to hurl themselves into tackles. If the sweeper does move up the field to distribute the ball, they will need to make a speedy recovery and run back into their position. In modern football, its usage has been fairly restricted, with few clubs in the biggest leagues using the position.