This is how Christian Eriksen could hurt Arsenal in the North London Derby

Traditionally the three center back system developed in order to provide a simple way to man-mark multiple center forwards. With the 4-4-2 in vogue, teams decided to go to three at the back so that two center backs could each mark the two strikers, leaving a third center back free to provide cover.

The problem is that when teams abandoned two striker systems and switched back to a lone striker, this created a basic systemic problem: If there isn’t a second striker to mark, what are the two center halves not in charge of man-marking a single player supposed to do?

When things go south for this system, it’s when they face a team with attacking players who move intelligently across the attacking third and use their positional sense to pull defenders out of position or find empty pockets of space where they can receive the ball and punish the opposition. These skills are valuable no matter what system you’re facing, of course, but against a back three with uncertain defensive responsibilities they can be especially disruptive.

Christian Eriksen is a master at finding bits of space. Arsenal has just switched to the back three in the past few weeks.

You know where this is going.

Christian Eriksen Against Chelsea

The funny thing about this is that theoretically a three at the back system should be able to deal with our 3-5-2 without too much trouble. The central defender takes Harry Kane, the two wide defenders take Dele and Eriksen. This is where Eriksen’s movement complicates matters.

While Dele plays as a second striker, looking to make aggressive vertical runs into the box and play off of Harry Kane, Eriksen actually plays as an odd kind of attacking midfielder/central midfielder hybrid. At times he drifts forward into a sort of right attacking midfield role reminiscent of David Silva. At other times he drops off into midfield and plays as more of a right-sided central midfielder opposite Mousa Dembele and just ahead of Victor Wanyama. This is why Chelsea had such trouble marking him.

This shot is from one minute before Tottenham’s opener in the last league fixture with the Blues at White Hart Lane. Note where Eriksen is sitting. Who is supposed to mark him?

Eriksen is right in the middle of a square formed by, going clockwise from the top, Marcos Alonso, Eden Hazard, Nemanja Matic, and Gary Cahill.

Here we are a few seconds later and you can now see what will happen to Eden Hazard: He will push forward defensively to pressure the midfielder or defender on the ball. Given the quality creative defenders Spurs have as well as Mousa Dembele’s dribbling ability, that’s an entirely reasonable move. But it means that now Hazard can’t help on Eriksen, so Matic, Alonso, or Cahill needs to mark him.

So what happens when one of those three players have to mark Eriksen and Eriksen’s movement makes it almost impossible for them to determine who actually tracks him? Here you go:

Look at that space he is in when he gets the ball. Cahill has dropped off. Matic and Alonso tracked Walker. And, significantly, Eriksen did not make a vertical run into the box, but instead dropped off and made himself available for an easy layoff from Walker. Result: Goal.

The second goal played out much the same way:

Eriksen plays the ball wide to Walker, multiple Chelsea players flow to Walker, leaving Eriksen in tons of space on the edge of the area.

How will this play out against Arsenal?

Well, Eriksen did this to Chelsea. Chelsea have legitimately excellent defenders and central midfielders, had been playing the system for several months, and are managed by Antonio Conte, who had his Juventus playing three at the back for most of his four years at the club.

Arsenal have maybe one legitimately good center back and several mediocre-to-OK ones. They have some great midfielders, but none are adept at holding or shielding the defense. They have been playing three at the back for a few weeks. They are managed by Arsene Wenger, who hasn’t played three at the back... ever, I think?

Eriksen could terrorize the Arsenal defense.

Could Arsenal just play their normal 4-2-3-1?

They could, but that doesn’t necessarily fix the problem. One way of dealing with Eriksen’s movement is to try and have a midfielder tracking him, cutting off passing lanes, and limiting his time on the ball. Arsenal’s midfield options include Aaron Ramsey, Granit Xhaka, Mohamed Elneny, and Francis Coquelin—none of whom excel at tight man-marking or covering the sort of ground required to track Eriksen.

Moreover, switching to 4-2-3-1 would mean sacrificing a defender for an attacker, which simply creates a new problem for Arsenal as that may make it harder to limit Mousa Dembele’s effectiveness on the ball or to keep tabs on Dele Alli.

How can Arsenal control Eriksen?

The most comprehensive beatings that Spurs take under Mauricio Pochettino tend to have something in common: Teams take the game to them, denying us time on the ball when we are in possession and passing through our press when they have possession. The Manchester City draw and Liverpool defeat, probably the two worst performances we’ve had this season, both share that same basic trait. Put simply, you beat Pochettino’s Tottenham by replicating their preferred plan and doing it better than they do.

If Arsenal can regularly break through the first layer of the press, it could give Tottenham trouble. Moreover, if Alexis’s industry up top (and perhaps also Danny Welbeck’s?) can limit Toby and Jan’s time on the ball or force Eric into a few turnovers, that could both disrupt our attack and create some chances for Arsenal.

If this is going to happen, Arsenal will need a composed performance in defense from Laurent Koscielny and whoever partners him (assuming Koscielny plays, which is currently in doubt).

They will also need their front six to be ready to hassle and harass the Tottenham midfield and defense in order to deny players like Eriksen, Dele, and Harry Kane regular service. If the Spurs attacking three is routinely getting the ball in dangerous positions, Arsenal will be in trouble. (If Spurs go back to 4-2-3-1, then Arsenal will also need to be limiting Son’s touches as well.)

To be sure, Arsenal is capable of that. Alex Oxlade-Chamberlain, Alex Iwobi, Alexis Sanchez, and Danny Welbeck can all press when called upon to do so. Aaron Ramsey and Laurent Koscielny can be clever, sophisticated passers. So Spurs fans should not be over-confident heading into this fixture even if, on the evidence of this season, we are the superior team. Rivalry games are always wacky and Arsenal is theoretically capable of doing the things that teams need to do in order to beat us.

Even so, the thought of Christian Eriksen going up against a defense that is still learning to play three at the back and that may include Rob Holding should Koscielny miss through injury... well, that sounds awfully promising.