THE North London derby will be a fascinating clash between a title-chasing Spurs and an Arsenal side desperate for Champions League football.
It is fair to say that a draw tomorrow is not good for either side.
Only a win will suffice for both Mauricio Pochettino and Arsene Wenger.
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It should make for an entertaining match — more so than the Manchester derby on Thursday.
What makes it so interesting from a tactical point of view is that the two sides will be essentially deploying the same formation: 3-4-2-1.
For Tottenham, this is the system that suits them best. They have been drilled meticulously by Pochettino on the training ground throughout the season.
Their wing-backs — Kyle Walker and Ben Davies, in the place of the injured Danny Rose — have been sensational and turned the club into a real Prem force.
Toby Alderweireld, Eric Dier and Jan Vertonghen have all played in the full-back positions before.
Unlike most centre-backs, they are quite capable of going outside the width of the 18-yard box.
And that means if the ball does go over the head of Walker or Davies, it is not a major issue.
One of the three centre-backs can immediately switch to full-back (Plan A).
Then someone like Victor Wanyama is comfortable to drop into central defence. So essentially Tottenham move into a back-four when defending.
Arsenal switched to a three-man defence for their match at Middlesbrough two weeks ago. The idea was to make the Gunners defensively sound.
The decision by Wenger was to stop them leaking so many goals. They had conceded ten to Bayern Munich, three to West Brom and three at Crystal Palace.
Since making the tactical chance, they have beaten Boro (2-1), Manchester City (2-1) in their FA Cup semi-final and then Leicester (1-0) at home.
Clearly it has worked. But they have to be careful at White Hart Lane tomorrow afternoon.
Like with any new system, it takes time to adjust to it. For Wenger, this was one of the boldest tactical changes of his career. But Arsenal will have to keep an eye on the distance which develops between the back-three and defensive midfielders (Plan B).
At times against Middlesbrough, central midfielder Granit Xhaka played far too ahead of his defence.
This left gaps. OK, so Boro were unable to exploit them. But Spurs probably would.
It is these gaps which the likes of Dele Alli, Christian Eriksen and Mousa Dembele — if he is fit — will love to get into.
Either the Arsenal back-three have to push up higher, or Xhaka has to be more disciplined.
Also, Arsenal’s wing-backs need to make sure they are not susceptible to the Tottenham counter.
The likes of Kieran Gibbs, Nacho Monreal, Alex Oxlade-Chamberlain or Hector Bellerin may get beyond a Walker or a Davies.
But Arsenal do not have centre-backs to move into the full-back positions, other than Monreal.
When turnover happens with possession, more often than not Walker or Davies get the wrong side of their full-back and have space to run into.
Tottenham’s front three of Eriksen, Harry Kane and Dele all play quite narrow.
So Arsenal’s centre-backs cannot afford to go into wide positions to cover their wing-backs and combat Walker and Davies. That would leave them outnumbered in the middle.
The role of the wing-back has changed massively. In the past, the full-back might occasionally overlap the winger — but now the wing-backs have the entire width to work with.
They have to get the balance right between offering an attacking threat, yet not being exposed when they do not have the ball.
For years, most teams played with a flat back-four. But Prem clubs, led by Chelsea and Spurs, have gone with three instead.
With three at the back, you can have two defenders marking the forwards and one sweeping.
When I played, the standard formation was 4-4-2 or even 3-5-2. Footballers these days have to be more flexible and adaptable.
Managers have more impact now, the game is more tactical.
Small tweaks can be the difference in games between top-six teams.