The 421 formation seems conservative (4 defenders and 2 backs), but this formation does not play a lot on the offensive end, and the team will have a considerable chance to gain a score advantage after taking the ball.
Clear defensive tasks, in order to play the formation advantage!
Forward: Although this formation has a clear numerical advantage on the defensive line, this does not mean that the forwards do not have a defensive task. Strikers must keep an eye on the opposing centre-back when defending, and cannot let the centre-back cross the center line too easily. Because the number of people in the 421 formation is small, the opposing formation will wait for the opportunity to move forward and compress our formation. We have less room to handle the ball in the midfield, so it will be difficult for the team to unfold even after it has the right to play.
Midfielder: Don't get out of your feet easily, stand in place. Avoid as much as possible the situation where the defender line is facing the person with the ball directly opposite. Not out of the foot does not mean not to oppress, more use of the body to go to the main position of the card, so as to prevent the opponent from shooting long-range.
Defender: The number of defenders in the middle is obvious, and if the various areas can not lose their positions, it is not easy for the opponent to enter the box. But proper footing is allowed in order to win the ball, and the full-back must always suppress the opposing attacking players on the flank and strive to win the ball. And the centre-backs have to protect the same side-backs, and the defender line has to make a sense of hierarchy!
Offense has to hit more gaps
Forwards: Because the number of attacking players in the midfield is not dominant, the range of movement of the forwards is required to be larger. (The effect of being able to run 2 people is the most ideal state) More retracement midfielders form a contact point, opening up the forward slot for teammates on the no-ball side. (Note that when you retrace, handle the ball crisply, don't force a turn, so it's easy to lose the ball!) ）
Midfielder: Play with the full-back on the side of the ball, which requires both sides of the pass to move (after passing can not stand still), can not stick the ball in the case of no dominant number of midfielders, handle the ball concisely and clearly (can handle the ball with one foot resolutely without two feet). The midfield on the other side is inserted at the right time, and the opponent is in the gap behind the opponent (the non-ball side pays attention to the rotation of the player, the midfield is inserted, and the defender on the other side has to make up for the protection of the midfield, try to avoid the situation that the full-back on the side of the ball is inserted at the same time and the midfielder is inserted at the same time).
Defender: This formation requires full-backs to be bolder and more agile when attacking, and the full-backs' running positions will not be straight up and down (part of the midfield when attacking without the ball). When the full-back on the side of the ball is pressed, the center-back near the side should move to protect the position behind him.
Although the 4-back gives people a conservative feeling, in fact, the essence of this formation is to solidify the defense and take the ball in the simplest way to hit the opponent's gap to form a threat, and the team can derive a lot of routines on the offensive end.