Let's talk about PSG. Why are they so difficult to defend? A look at their wide triangles, high mobility, large distances and positional play principles, exploring the tactical dilemmas they create and how different teams have tried to stop them. It's a clear 3+1 structure, with the two centre-backs and the left-back staying deeper, plus Vitinha usually in front of them. Then we have two wide triangles, one on each side. Both wingers provide the full width, while the attacking midfielders on each side, Fabián and João Neves, have the responsibility of joining those wide triangles. As you can see in the picture, João Neves doesn't approach the ball; he has a positional responsibility to stay on the far side. In those wide triangles, we can see a lot of mobility between the three players. PSG plays with very large distances, with a lot of mobility in the wide triangles but with clear positional play principles. To understand why it is also positional, we can take a look at Vitinha. Vitinha usually stays in front of the defenders, but occasionally, he likes to make runs and join the wide triangles. Immediately, you will see Fabián Ruiz or João Neves dropping to occupy the space Vitinha has left, maintaining the same structure. Vitinha is so important for them because he is the player in charge of connecting both triangles and bringing the ball from one triangle to the other. It's common to see Vitinha receive under pressure next to one of the triangles, play a quick one-two to beat his direct opponent, and then carry the ball to the other triangle. This tends to be faster and safer than the typical long switch of play that many teams use, which I feel gives the opponents more time to drop back. The wide triangles are difficult to defend. If you play the offside trap, it doesn't work as well for FC Barcelona as it does against other teams. The offside trap works well to disconnect the first-wave runs. But the wide triangles, with their high mobility, are meant to take advantage of second-line runs, for example, from Hakimi, the right full-back, or Fabián/João Neves, the attacking midfielders. If you defend zonally, you will protect the ball side better, but on the far side, you might end up having one player less. Look at this picture. FC Barcelona are defending in a zonal 4-2-3-1, with Rodri defending zonally and protecting the space on the ball side. The play ends up with João Neves on the far side, creating a clear 3v2 situation. There is another aspect PSG looks for by separating both triangles so much. If the opposition goes man-oriented in both triangles, you are giving the wide triangle much more space to operate, freeing up space for those runs to happen by taking away the coverage function that zonal defending can provide. Kompany mentioned last season that an "in-between" defensive posture doesn't work against PSG, and decided to go full man-to-man. "You either go full attack or drop completely back into a deep block." With this approach, my feeling is that you become highly dependent on the quality and athleticism of your players. The fact that PSG don't have to play their strongest starting XI every weekend can be an advantage for them. Arteta opted for the second option, dropping into a deep zonal 4-4-2 block, but with the two midfielders protecting the half-spaces, at times becoming a 6-4-0. It worked well defensively, but lacked a threat in offensive transitions. The best team I have seen play against PSG was Chelsea under Enzo Maresca in the Club World Cup final. They played very man-oriented also in deeper areas, while trying to prioritise a +1 at the back, but still keeping a front three higher up to try to punish PSG in transition and exploit their 3+1 rest defense. In that game, Pedro Neto tracked Hakimi all the time.