At the end of an arduous festive period of fixtures, Chelsea travel to the Emirates Stadium on Wednesday night to face their London rivals Arsenal.

Both sides have had a rather relaxed series of fixtures over the holiday period. The fixture computer decided to be kind, as Arsenal and Chelsea have had at least two days’ rest between each fixture in December.

As it stands, both sides are in decent form. Chelsea have lost just once in their last 13 Premier League fixtures, while Arsenal’s two defeats were to both Manchester clubs in that same number of Premier League fixtures.

But Arsenal and Chelsea’s injury situations are far different. Aside from the continued absence of David Luiz, Chelsea’s squad are all available for the match against the Gunners, while Arsene Wenger sweats over the fitness of Nacho Monreal, Mesut Ozil, Laurent Koscielny, and Sead Kolasinac. Olivier Giroud and Aaron Ramsey remain out.

What formation will Arsene Wenger play?

A big point of debate this season for Arsenal is the formation that should be played. Wenger tinkered with a back three last season to some degree of success, and continued using that formation in the first half of the season.

But as injuries and loss of form have started to become an issue, Wenger has reverted to a back four as either a tactical switch during a match or to compensate for various injuries.The interesting thing is that Arsenal have looked far more solid defensively in a back four as opposed to a back three, and with Kolasinac out, and Monreal and Koscielny questionable, Wenger will have a decision to make.

When they’ve played a back three this season, teams have exposed their weakness to the counter attack. While the third centre back is supposed to offer an extra man to cover in defence, that doesn’t always help Arsenal.

In Arsenal’s back three, the wing backs provide the width as they should, but Arsenal’s problem tends to be with the outside centre backs and their holding midfielders. When the wing backs press on, the outside centre backs push wider to cover the space behind the wing backs, but because Arsenal don’t have any true holding midfielders, their centre midfield likes to play further forward, they don’t cover the space in front of the centre backs and give up a lot of 3 v 3 situations.

When they play a back four, that doesn’t happen as often because Ozil often plays as a number 10 and allows them to play a three-man midfield, which ironically forces one of their midfielders to act as cover.

With the injuries Arsenal have, it’s likely that young Ainsley Maitland-Niles is going to be asked to play on the left side of defence. Wenger may want to offer the young wing back a chance to not have to worry as much about defending and opt for a back three, but with injuries, that back three will lack pace, as Shkordran Mustafi, Per Mertasacker, and Calum Chambers will likely start.

Wenger has to get his selection right, or the Emirates could be an unhappy place on Wednesday night.

Chelsea’s record against Arsenal under Antonio Conte is not great, but if Chelsea take control early, the Emirates could get restless.

In the last five fixtures between Chelsea and Arsenal, Chelsea haven’t had the best of times against the Gunners, with just one win, two draws, and two defeats.

It’s safe to say that Antonio Conte hasn’t had the best of times against Wenger since taking the Chelsea job, and the last time Chelsea travelled to the Emirates, it was the infamous 3-0 Arsenal win that prompted Conte’s legendary tactical change.

Things have definitely changed since that time. Arsenal always seem one major defeat from a mild catastrophe, and that almost happened against Liverpool on 22 December when the Merseyside club romped out to a 2-0 lead against a shambolic first-half performance.

On that occasion, the Gunners were able to pull themselves out of the hole to take the lead in the second half, only for more shocking defending leading to a Liverpool equaliser.

But that was Liverpool, a team with their own defending issues, and one who always look like conceding, and this time, it’s Chelsea, a side that can take the fight out of the opposition if they take an early lead.

The Emirates is always a bundle of nerves when Arsenal play poorly, and Chelsea must assert themselves in the match at some point and trust that they will score against a depleted Arsenal side and possibly turn up the nervous energy in the crowd.

The one thing Chelsea cannot let happen is what happened in last year’s FA Cup Final, where Arsenal started out pressing with energy and rattled Chelsea with their incessant pressure. Whether Arsenal have the legs to do that on Wednesday night is questionable, but Chelsea might have to just ride the early stages and not let Arsenal grow in confidence by scoring a very early goal.