Including their Champions League defeat to Napoli, Arsenal are without a victory in three games. If results go against them this weekend, Arsene Wenger could see his side drop to fourth in the Premier League table.
Even so, the Blues remain in touch with Arsenal and are in a position to overtake them with a win at the Emirates. If this was to occur, it would mark the first time the Gunners have dropped from the summit since August.
While this would obviously not be enough to induce panic, it would raise some questions about Arsenal's title credentials and there would be some pressure on Wenger to spend in January. The heavy defeat to Manchester City did humble them, so a victory is absolutely vital on Monday.
For his part, Jose Mourinho has already stated that he is unhappy with the amount of goals Chelsea are scoring. Speaking to Sky Sports, he outlined some areas in which things haven't gone to plan:
The base of our game is to kill opponents by scoring goals, because we don't want to go in the direction of being a more defensive team.
This is the easy direction to go: to build a team, to close the team, to make it compact, to wait for a goal, waiting for a counter-attack.
This is not what we want to do and because it's not what we want to do, the way to kill opponents is to score goals.
While Mourinho will have been encouraged by watching Manchester City put six past Wojciech Szczesny last week, his players have recently been wasteful in front of goal. This cannot continue at the Emirates.
Arsenal will be without Jack Wilshere, who starts a two-match suspension. Alex Oxlade-Chamberlain (knee), Abou Diaby (knee) and Yaya Sonogo (back) also remain absent for the Gunners.
The knee laceration that cause Laurent Koscielny to be stretchered off against Manchester City is causing him to be a "major doubt" for the Chelsea fixture, according to David Wright at the Express.
In better news for Wenger, Lukas Podolski is once again available after missing three months with a hamstring strain.
For Chelsea, Michael Essien is suspended after picking up his fifth yellow card of the season, but Mourinho will be buoyed by the return of John Terry. Ashley Cole, meanwhile, is likely to start on the bench after the Daily Mail reported that Mourinho was less than impressed with the left-back attending the Arsenal Christmas party last week.
Mesut Ozil, Arsenal
When Mesut Ozil plays well, Arsenal usually win. However, Mourinho will know his game well from his days at Real Madrid and will look to frustrate him.
Ozil has more assists than anyone in the Premier League (7) but also needs to deliver in games of high importance for Arsenal. Against both Manchester City and Manchester United, he struggled to get a real hold on the game and the midfield suffered as a result.
He has the ability to turn a match with a few seconds of brilliance and Arsenal will need it from him on Monday.
However, Mourinho has never lost to Wenger and will be keen to retain that record. Stopping Ozil will be the key to Chelsea leaving the Emirates with a result.
Arsenal 1-1 Chelsea