Arsenal will go into the match knowing that defeat could leave them six points adrift of the Champions League places too, so there is plenty riding on Arsene Wenger's 812th Premier League match at the helm.
Chelsea, meanwhile, will leapfrog Manchester United into second place with a victory at the Emirates, and they go into the game having won four of their last five Premier League matches.
Here, Sports Mole selects a combined XI from both squads in a 3-4-3 formation, with only players available for Wednesday's match under consideration.
GK: Thibaut Courtois
Only Manchester City have conceded fewer goals than Chelsea in the Premier League this season, and that is largely down to the presence of Thibaut Courtois between the sticks.
The Belgian has played every minute of Chelsea's title defence so far, and only Manchester United's David de Gea has kept more clean sheets than him in that time.
Arsenal's candidate is Petr Cech, who of course enjoyed an 11-year stay at Chelsea, but the Czech lost his place at Stamford Bridge to Courtois and also misses out on a spot in this team to his former clubmate.
Quite possibly the first name on the Chelsea teamsheet week after week, Cesar Azpilicueta continues to put in consistently quality performances whether he is on the right side or at the heart of the defence.
The Spaniard has played most often on the right side of the back three this season, and that is where he lines up in this team too.
Despite his reputation as one of the league's most solid defenders, Azpilicueta can also pose a threat at the other end of the field, having scored one goal and registered six Premier League assists this season - the latter of which is a tally only five players can beat so far this term.
One of Chelsea's revelations this season has been Andreas Christensen, whose form since returning from a two-year loan spell at Borussia Monchengladbach has seen him seemingly move above the likes of David Luiz, Gary Cahill and Antonio Rudiger in the pecking order at Stamford Bridge.
Christensen averages more blocks per match than any other player in the Chelsea squad, and the 21-year-old has even been tipped to go on and enjoy a career similar to that of John Terry.
Chelsea have conceded just 14 times in their 21 matches so far this season and have kept eight clean sheets in the 15 Premier League games featuring Christensen.
CB: Shkodran Mustafi
Arsenal have their injury problems in defence at the moment, with Nacho Monreal expected to miss Wednesday's game and Laurent Koscielny also a major doubt, but they still earn a representative in the back three through Shkodran Mustafi.
The German has arguably been Arsenal's best player this season, averaging more tackles and clearances per game than any other regular member of the first team at the Emirates.
Chelsea pair Cahill and Rudiger could also lay claim to this position but Mustafi - who has also weighed in with two goals this term - gets the nod instead to complete the back three.
RWB: Hector Bellerin
It is fair to say that Hector Bellerin's stock has slipped a little so far this season. Once considered one of the brightest young full-backs in the game, he can at times be seen as something of a liability by increasingly disgruntled Arsenal fans now.
However, the Spaniard is still only 22 years old and remains an important part of Arsenal's team, starting all 21 of their Premier League matches and playing every minute so far this season.
The Chelsea competition arrives from Victor Moses, but the winger has missed a large chunk of the season through injury and is only now beginning to get back up to full fitness again.
CM: N'Golo Kante
A player who would probably make it into every combined XI in the Premier League, N'Golo Kante has once again proven to be an incredible force in the middle of the park for Chelsea this season.
Only two players have averaged more tackles per game in the entire division than the reigning PFA Players' and FWA Footballer of the Year, who has also helped himself to a rare goal at the other end too.
Arsenal's own defence-minded midfielder is Granit Xhaka and, despite the Swiss international having well and truly established himself in Wenger's team now, Kante is a very easy selection ahead of him.
CM: Cesc Fabregas
Arsenal will need no introduction to Cesc Fabregas, and the Spaniard is sure to be treated to a few boos and jeers on his return to the Emirates Stadium on Wednesday.
Fabregas is not always a guaranteed starter in the Chelsea team with Tiemoue Bakayoko and Danny Drinkwater also vying for a place alongside Kante, but the Spaniard remains one of the most creative and crafty players in the Premier League.
With Aaron Ramsey expected to miss out again Arsenal's main candidate for this place comes from Jack Wilshere, but Fabregas - who has two goals and five assists across all competitions this season - earns his place above his former teammate.
LWB: Marcos Alonso
When it comes to attacking threats from defence, Chelsea's Marcos Alonso takes some beating over the past season-and-a-half since his arrival at Stamford Bridge.
The Spaniard scored six times and registered three assists in the Premier League last term, and after only 21 games of this campaign he is already on five goals and one assist.
Arsenal's Sead Kolasinac is likely to miss Wednesday's match due to injury, leaving Alonso as the only real choice for the left wing-back position in this team.
RW: Eden Hazard
Eden Hazard may not have been at his brilliant best in recent weeks, but even when he is not on the scoresheet he remains a constant danger, capable of bursting into life and winning a game in the blink of an eye.
The 26-year-old has scored eight goals and created four more across all competitions for Chelsea so far this season and would be deployed in a free role in this team, able to roam all over the final third in order to do maximum damage.
Arsenal's standout competitor for a place in the team is Mesut Ozil, but the German is a doubt for Wednesday and Hazard would be almost impossible to leave out of any combined XI in the Premier League anyway.
CF: Alvaro Morata
Alvaro Morata's physical presence and aerial ability seemed to be perfectly suited to the Premier League when he joined Chelsea last summer, and that has proven to be the case with the Spaniard enjoying a productive first half of the season.
Six of Morata's 10 Premier League goals have come via headers, while he has also contributed four assists for his teammates from his 18 outings in the league.
Arsenal's Alexandre Lacazette has also had his moments since moving to England at the start of the season, but he is unable to match Morata in goals, assists or average number of shots per game.
LW: Alexis Sanchez
Every time Alexis Sanchez takes to the field now, Arsenal fans must be wondering whether it is the last they will see of the Chilean.
Sanchez's attitude has been called into question this season - to the extent that there is even talk of a rift in the squad because of it - but he is still Arsenal's joint top-scorer across all competitions with eight, in addition to three assists in the Premier League.
The likes of Willian and Pedro have both been in good form for Chelsea, but Sanchez remains one of the league's most talented players and is a fairly easy choice to join Hazard and Morata in a deadly front three.