Centre backs are usually are in pairs, with 2 full-backs to their left and right, but can come in threes with no full backs
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 specialized 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 have included John Terry and Ricardo Carvalho with Chelsea, Sergio Ramos, Raphaël Varane or Pepe with Real Madrid, Nemanja Vidi? and Rio Ferdinand with Manchester United, or Giorgio Chiellini, Leonardo Bonucci, Andrea Barzagli and Medhi Benatia 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.
Some centre-backs have also been known for their direct free kicks and powerful shots from distance. Brazilian defenders David Luiz, Alex, and Naldo have been known for using the cannonball free-kick method, which relies more on power than placement.
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 tracking 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 "roamed" only 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. 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.
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 players such as Daniele De Rossi, Leonardo Bonucci, Javi Martínez and David Luiz 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, Edwin van der Sar, Fabien Barthez, Marc-André ter Stegen, 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 early decades of football under the 2-3-5 formation, the two full-backs were essentially the same as modern centre-backs in that they were the last line of defence and usually covered opposing forwards in the middle of the field.
The later 3-2-5 style involved a third dedicated defender, causing the left and right full-backs to occupy wider positions. Later, the adoption of 4-2-4 with another central defender led the wide defenders to play even further over to counteract the opposing wingers and provide support to their own down the flanks, and the position became increasingly specialised for dynamic players who could fulfil that role as opposed to the central defenders who remained fairly static and commonly relied on strength, height and positioning.
In the modern game, full-backs have taken on a more attacking role than was 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 a heavier emphasis on attack. Wing-backs are almost exclusively used in a formation with 3 centre-backs and are sometimes classified as midfielders instead of defenders. In the evolution of the modern game, wing-backs are the combination of wingers and full-backs. As such, this position is one of the most physically demanding in modern football. Successful use of wing-backs is one of the main prerequisites for the 3-5-2 and 5-3-2 formations to function effectively. 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 may be 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 and current Inter Milan manager Antonio Conte.