The tactics column looks at the 4-2-3-1 formation and how it has become almost the standard in modern football because of its balance and flexibility.
The 4-2-3-1 splits players into four bands. The defensive unit consists of the standard centre-backs and full-backs and two defensive midfielders screening them, often called the ‘double pivot'.
The attacking unit consists of a band of three attacking midfielders and a lone central striker. The wide midfielders are generally fast dribblers who like to cut inside or make runs into the box. The attacking central midfielder, often the ‘No. 10', is normally a creative passer who can play balls into the feet of either the wide attackers or the lone striker.
A good 4-2-3-1 is a formation that has a wonderful ‘springy' quality - it absorbs pressure without breaking and then snaps back with surprising force.
In defence the 4-2-3-1 covers space very effectively, with the band of three and the lone striker able to press the opposition high up the pitch while the two defensive midfielders ensure that there is no space left in front of the defence. Then the back four can either play a high line, compressing the space even further, or drop deeper as preferred.
Video analysis: Jose Mourinho's 2014-15 blue wall at Chelsea
Chelsea were dominant in 2014-15 as Nemanja Matic and one of Cesc Fabregas or John Obi Mikel formed a stable ‘double pivot' at the base of the Chelsea midfield to release the attacking unit of Hazard, Oscar, Willian and Costa up top.
This Sky Sports analysis of their December 2014 win over Stoke City shows how Jose Mourinho set-up Matic and Mikel to win the ball in midfield and then release the attackers. A good example of the 4-2-3-1's flexibility as Mourinho opted for a more defensive double pivot against a physical side.
Once the ball is won back, often by the defensive midfielders, the 4-2-3-1 can spring into attack.
The full-backs can surge up the wings in the knowledge that the defensive midfielders can drop into the space left behind if needed. As they come up the wings, the wide attackers come inside and they tend to be fast dribblers who look to get into the box. The attacking central midfielder, often the ‘No. 10' who is the most creative player on the team will look to play them or the lone striker in via fast passing combinations.
Arsene Wenger loves an attacking midfielder and the combination of Theo Walcott as a lone striker, supported from left to right by Alexis Sanchez, Mesut Ozil and Aaron Ramsay ripped Manchester United apart inside 20 minutes in October 2015 with their rapid passing combinations.
Note for the first goal how first Hector Bellerin provided width from the full-back position but lost the ball and then Francis Coquelin, playing as one of the two defensive midfielders, won it back behind him to continue the attack. A perfect demonstration of the how the 4-2-3-1 covers space.
If the rapid attack fails, the 4-2-3-1 is well set-up to either retain possession, with a large number of passing triangles naturally formed by its four bands of players, or to press and regain the ball quickly.
While at its best the 4-2-3-1 is a masterpiece of flexibility, when played poorly it can be slow and cumbersome.
If the midfield bands are forced back and compressed into a 4-5-1, the striker can be left isolated with very little support. The full-backs, key to modern attacking football, can also be trapped behind their midfield line.
Or the opposite may happen, where the attacking band of midfielders neglect to track back and help their full-backs, allowing opposition wide players to overload the defence. This is similar to the possible problems in a 4-3-3, if the attacking wide players forget their duty to help the team when out of possession. However it can be even more pronounced as the two defensive midfielders are left with a huge amount of the pitch to cover.
Video Anaylsis: Chelsea's 2015-16 nightmare
After dominating the Premier League one season in the 4-2-3-1, Jose Mourinho and Chelsea had a horrific start to the season with the same formation. The most obvious problem was the failure of their defensive midfield to cover their back four, as they were left isolated by the attacking band of midfielders - as analysed in this Sky Sports video of their 3-1 loss to Liverpool.
How the 4-2-3-1 took over the world
Juanma Lillo, former Real Sociedad coach, is generally accepted to have been the first to consciously use the 4-2-3-1 in pursuit of the best distribution of players across the pitch to achieve two key aims - possession and pressing, retaining the ball and regaining it quickly.
Since its adoption by many teams in Spain in the 1990s it spread rapidly in the early 2000s as detailed by Jonathan Wilson of the Guardian here. The switch from a 4-4-2 is relatively easy - one striker drops back to become the creative, attacking midfielder, the wingers push forwards and instead of staying out wide and putting in crosses they become dribbling attackers and the central midfielders drop deeper to make the ‘double pivot'.
Since then the extraordinary success of Pep Guardiola's 4-3-3 ´tiki-taka' at Barcelona (see my analysis of the 4-3-3 featuring that team here) has provided an alternative to the 4-2-3-1 but the principles that Guardiola adheres to - retain the ball and regain it quickly when lost - are the same identified by Lillo and for teams which want to achieve those aims while also having flexibility the 4-2-3-1 is still the most popular choice.
More articles in the 7500toHolte Football Tactics Basics series can be found here: