Let's have a look at how @SheffieldUnited broke down @ChelseaFC's set-piece defense to score the first goal.

We'll start with as soon as the corner is taken:

Key things:

a) Sheff. Utd. have three *anchors* - players that will lock down certain Chelsea players. This will be key

Sheffield pass short and this brings out Kante and Ziyech with Kante going to the short-receiver with Ziyech shaping up his run to track the other Sheffield player who is running down to provide width.

Keep your eyes on the anchors still.

This is where Chelsea make a mistake. Both Ziyech and Kante are - falsely - drawn inwards with one Sheff. Utd player holding his position.

The anchors still stick to their markers but now two attackers have entered the forray. Notice how they are right behind the anchors...

The ball gets released and we see an interesting movement.

The new "attackers" make runs into the box drawing the defensive line forward. The anchors then stay back creating space. Here, Brewster - an anchor - joins in with the penetrating runners to add support.

The end result is Sheffield have created a lot of space right in the penalty area and the flick by McGoldrick is just the cherry-on-top on what is a well-worked and executed routine.

In essence, the anchors hold down the defenders enough for the runners to then pick up and move the line.

The anchors then just stay back having a lot of space.