The 4-3-1

Target Formation
The 11v11 formation that is mimicked by the 4-3-1 is the 4-4-2.

Positioning
The standard 4-3-1 features four fullbacks (two center halves in the middle of the field and two outside fullbacks positioned higher up the field than the center halves), three central midfielders arranged in an inverted triangle shape with a holding midfielder (#6) at the base, and one forward in the most advanced position.

Attacking Philosophy
The 4-3-1 is a conservative, possession-based formation that relies heavily on the skill, stamina, and intelligence of the holding midfield player (#6). Playing in the space in front of the center halves, the #6 is the primary ball possessor and distributor in the 4-3-1. The forward (#9) is the focal point of the attack. The attacking midfielders make runs into and out of spaces left in the defense by the forward, seeking to exploit gaps. The center halves provide support for the holding midfielder and often switch the direction of the attack from the back line. The outside backs typically push high up the field in the attack to provide support for the midfielders and forward and to increase the pressure placed on the opposing defense. The outside backs also make runs along the wings to cross balls into the box. The objective of the attack in the 4-3-1 is to possess the ball at progressively more advanced positions on the field by widening the field with the positioning of the outside backs and the movement of the forward and attacking midfielders. The ball handling and distribution skills of the center halves are utilized more in the 4-3-1 than in formations with only one center half. The origin of the attack in a 4-3-1 is deeper than in other formations and typically progresses up the field indirectly, with drops and changes of direction in abundance.

Strengths
When played well, the 4-3-1 can dominate ball possession. The employment of all four fullbacks in the attack is challenging to defend, especially when the outside backs play wide and open vast empty spaces to exploit. 

Weaknesses
The 4-3-1 is vulnerable to counterattacks if the outside backs are in advanced positions when possession is lost. Intelligent and athletic opponents can attack the space between the center halves and cause confusion on the back line, resulting in more attacking space for players moving forward.

When to Employ the 4-3-1
The 4-3-1 is an effective formation for teams with a large number of players skilled in possession. Because the attack usually is indirect, the 4-3-1 values patience and distribution over speed and athleticism.

Derivatives

4-3-1 Diamond
The 4-3-1 Diamond features a diamond shape among the fullbacks, with one center half at the base, one center half at the top, and outside fullbacks to the left and right. The midfielders are aligned evenly (a "flat" three), and the forward plays as the forward plays in the standard 4-3-1. These alterations to the standard 4-3-1 result in a direct, wing-based attack. The more advanced center half is the primary ball possessor and distributor, with the central midfielder pushing higher to support the forward and to serve as a central target for the outside midfielders and fullbacks. Effective 4-3-1 Diamond attacks often feature rapid movement of the ball back-and-forth between the wings and the center of the field, which can create confusion in the opposing defense. The 4-3-1 Diamond is a more direct and aggressive formation than the standard 4-3-1, but is much more vulnerable to counterattacks.