There are four types of defenders: centre-back, sweeper, full-back, and wing-back. The centre-back and full-back positions are essential in most modern formations. The sweeper and wing-back roles are more specialised for certain formations.
A centre-back (also known as a central defender or centre-half) defends in the area directly in front of the goal, and tries to prevent opposing players, particularly centre-forwards, from scoring. Centre-backs accomplish this by blocking shots, tackling, intercepting passes, contesting headers and marking forwards to discourage the opposing team from passing to them.
With the ball, centre-backs are generally expected to make long and pinpoint passes to their teammates, or to kick unaimed long balls down the field. For example, a clearance is a long unaimed kick intended to move the ball as far as possible from the defender's goal. Due to the many skills centre-backs are required to possess in the modern game, many successful contemporary central-defensive partnerships have involved pairing a more physical defender with a defender who is quicker, more comfortable in possession and capable of playing the ball out from the back; examples of such pairings are John Terry and Ricardo Carvalho with Chelsea, Nemanja Vidi? and Rio Ferdinand with Manchester United, or Giorgio Chiellini, Leonardo Bonucci and Andrea Barzagli with Juventus.
During normal play, centre-backs are unlikely to score goals. However, when their team takes a corner kick or other set pieces, centre-backs may move forward to the opponents' penalty area; if the ball is passed in the air towards a crowd of players near the goal, then the heading ability of a centre-back is useful when trying to score. In this case, other defenders or midfielders will temporarily move into the centre-back positions.
There are two main defensive strategies used by centre-backs: the zonal defence, where each centre-back covers a specific area of the pitch; and man-to-man marking, where each centre-back has the job of covering a particular opposition player.
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.
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.
The position is most commonly believed to have been pioneered by Franz Beckenbauer, Gaetano Scirea, and Elías Figueroa, although they were not the first players to play this position. Earlier proponents included Alexandru Apolzan, Ivano Blason, Velibor Vasovi?, and Ján Popluhár. Other defenders who have been described as sweepers include Bobby Moore, Franco Baresi, Ronald Koeman, Fernando Hierro, Matthias Sammer, and Aldair, due to their ball skills, vision, and long passing ability. Though it is rarely used in modern football, it remains a highly respected and demanding position.
A recent and successful use of the sweeper was made by Otto Rehhagel, Greece's manager, during UEFA Euro 2004. Rehhagel utilized Traianos Dellas as Greece's sweeper to great success, as Greece surprisingly became European champions.
Although this position has become largely obsolete in modern football formations, due to the use of zonal marking and the offside trap, certain defenders such as Leonardo Bonucci, Sergio Ramos, David Luiz and Daniele De Rossi have played a similar role as a ball-playing central defender in a 3-5-2 or 3-4-3 formation: in addition to their defensive skills, their technique and ball-playing ability allowed them to advance into midfield after winning back possession, and function as a secondary playmaker for their teams.
Some goalkeepers, who are comfortable leaving their goalmouth to intercept and clear through balls, and who generally participate more in play, such as René Higuita, Manuel Neuer, and Hugo Lloris, among others, have been referred to as sweeper-keepers.
The full-backs (the left-back and the right-back) take up the holding wide positions and traditionally stayed in defence at all times, until a set-piece. There is one full-back on each side of the field except in defences with fewer than four players, where there may be no full-backs and instead only centre-backs.
In the modern game, full-backs have taken on a more attacking role than is the case traditionally, often overlapping with wingers down the flank. Wingerless formations, such as the diamond 4-4-2 formation, demand the full-back to cover considerable ground up and down the flank. Some of the responsibilities of modern full-backs include:
Due to the physical and technical demands of their playing position, successful full-backs need a wide range of attributes, which make them suited for adaptation to other roles on the pitch. Many of the game's utility players, who can play in multiple positions on the pitch, are natural full-backs. A rather prominent example is the Real Madrid full-back Sergio Ramos, who has played on the flanks as a full-back and in central defence throughout his career. In the modern game, full-backs often chip in a fair share of assists with their runs down the flank when the team is on a counter-attack. The more common attributes of full-backs, however, include:
The wing-back is a variation on the full-back, but with heavier emphasis on attack. This type of defender focuses more heavily on attack than defence, yet they must have the ability, when needed, to fall back and mark opposing players to lessen the threat of conceding a goal-scoring opportunity. Some formations have wing back players that mainly focus on defending, and some that focus more on attack.
In the evolution of the modern game, wing-backs are the combination of wingers and full-backs. As such, it is one of the most physically demanding positions in modern football. Wing-backs are often more adventurous than full-backs and are expected to provide width, especially in teams without wingers. A wing-back needs to be of exceptional stamina, be able to provide crosses upfield and defend effectively against opponents' attacks down the flanks. A defensive midfielder is usually fielded to cover the advances of wing-backs. It can also be occupied by wingers and side midfielders in a three centre-back formation, as seen by ex-Chelsea manager Antonio Conte.