This is part of How soccer works A series that takes a partial look at game mechanics
One good thing to do if you want to score goals is to receive passes behind the defensive line. This is usually difficult. Defenders like to stand close together in front of the box and will chase you if you run behind them, giving little consideration to your personal space. Frankly, they're rude.
However, sometimes the backline gets stretched. When the winger receives the ball on the sideline, the opposing full-back will sigh, tearfully bid farewell to his comrades and begin the long journey to the wing. He goes alone. This created a hole between the wing full-backs and their teammates at the top of the box, making it easier for the attackers to run behind the last line. It was as if someone had grabbed both ends of the protective fabric and torn it at the seams.
Sliding the ball through the hole behind the fullback and onto the wing is sometimes referred to as a 'seam run' and is a fundamental component of many attacking tactics. You've seen Pep Guardiola's Man City make strides like this for years. Many positional sides do it reflexively every time the ball goes wide. Just last week in the Champions League, Barcelona scored from a seam run and then Napoli scored a mirror-image goal against them.
Once you start noticing this pattern, it can feel like every soccer game is practically bursting at the seams.
The reason why coaches love seam runs so much is because there are four very easy ways to stop them, but each poses its own problems for the defense.
The most common way to defend a seam run is for the closest midfielder (usually already watching the inside attacker making the run) to follow the runner into the gap. The fullback is already positioned wide to the player with the ball, so he cannot chase him. The nearest centre-back could jump out and pursue the runner, but this would create a dangerous gap in front of the goal. The wide midfielder would then drop in to become an additional defender.
The challenge is awareness and timing. Since the marker starts in his second line of defense, he is not always able to watch the runs unfolding in front of them and know exactly when to turn and chase. It's very easy for runners to get behind them and start ahead on the seam, buying them the extra split second they need to get around the ball and get in the cross before their marker catches up.
That was the key to Barcelona's goal against Napoli. Center back Pau Kvarsi passed the ball to Joao Cancelo on the left, and Rafinha took his cue and began a seam run. Matteo Politano also recognized the pattern and at the same time instinctively started jogging to close the gap. However, he was on the wrong side of the runner and by the time he turned around to see if Rafinha was running his seam, it was too late to turn on the jets and catch up.
The second option for defending a seam run is for the backline to step up and catch the runner offside, rather than chasing. This is a dangerous maneuver so close to their own goal. If a pass goes awry or a winger tries to dribble past his marker, the attack will not only get behind, but will also catch the defense moving in the opposite direction. In other words, if you attempt this, it's better for all four or he five defenders to successfully complete the run.
When Napoli hit back with a seam-run goal in their own half, Barcelona barely managed to pull off the offside trap. In fact, it seems that Kbarsi was the only one who realized that that was what they were trying to do.
If Ronald Araujo and Jules Kounde had moved up behind Kvarsi, Politano's seam run would have easily been ruled offside, but if not, Barcelona had two problems. Cancelo entered the gap one step behind the runner. and The center back on the ball side was hopelessly forced out of position after failing the offside trap. Oops.
There are two more ways to shut down seam runs that aren't as sensitive to defensive timing, but both pose even bigger problems. That means showing your inner aggression.
The easiest way to cut off a seam run is for the fullback who is marking the player with the ball to run towards the sideline and block the passing lane. The problem with this defensive angle is that it opens up an inside route to the goal. If the ball carrier is reluctant to go in that direction, for example if a right-footed winger dribbles to the left and doesn't want to expose the ball, this may be worth the risk, but most of the time Attacking towards the line and away from the goal is Defense 101.
Alternatively, the defense could choose to slide the ball-side center back to shut down the seam runners, rather than chasing them with a reserve midfielder. This may seem natural, as centre-backs have a better view of the run and are more likely to arrive in a position to block a cross, but it is useful for centre-backs to keep strikers open in front of goal. It is extremely dangerous to leave it as is. Chasing wide runners.
Lazio committed both of these defensive sins in last week's Champions League match against Bayern Munich.
Rafael Guerreiro receives the ball on Bayern's left flank and Lazio's right-back Adam Marusic approaches from below, at an angle that blocks the passing lane for Jamal Musiala's seam run, but opens up a lane towards goal. Ta.
As he dribbled past Marzic, Guerreiro stopped and turned as if he was going to pass to Musiala anyway, fooling right centre-back Mario Gila into following the seam run and coming forward. With Lazio's full-backs and centre-backs out of the way, Guerreiro sent a free pass directly to Harry Kane in the box, confusing the defense.
Most seam runs don't result in a perfect cutback goal. Most players can't even receive the ball. In this sequence, they are just decoys like Musiala.
The reason teams like Bayern still make automatic seam runs every chance they get is because they ask so many dangerous questions for defenders: midfielders chasing runs out of position. Should he be dragged away? Should the full-backs block the passing lane and allow a path towards goal? Should the centre-backs step forward to track the run-out or try to catch it offside?
By the time the defense finds an answer, the seams may already be torn.
