Chelsea aren't playing very well. Maurizio Sarri warned everyone back in September that he felt Chelsea were a year or two behind their rivals and it looks like he had a point.

Former manager Jose Mourinho summarised things nicely on a rare TV appearance over the weekend: "I'm not saying Chelsea's an easy team to play against... but it's an easy team to analyse".

With that in mind, what's going wrong?

How Sarri-ball works

As has become all too apparent in recent weeks, Chelsea are predictable and easy to shut down. Sarri's team lineup in a 4-3-3, play a high defensive line and patiently wait for opportunities to score by passing, then passing some more, then passing even more, then passing even more than that.

The whole thing is structured around a deep lying playmaker, or 'six', acting as a link between centre-backs and midfield.

On either side of him are two central midfielders - 'eights' - who play from box to box and operate in the halfspaces. The wingers are instructed to move inside the pitch, full-backs play high and overlap and the striker has to be able to attack crosses, run onto through balls and link play.