#3 Fatigue

Chelsea's main man and striker Eden Hazard played out the entire 90 minutes against Fulham and Wolves in the past week. He has not enjoyed a minute of rest in both the games, and this might, in turn, affect his work rate and game on Saturday against the title leaders.
Sarri did not probably use him wisely, and it will be a silly move to start him against Manchester City this weekend. Eden Hazard has come on from the bench to give sublime performances for the Blues. One which I remember was against Arsenal, as he dribbled past Hector Bellerin and Mkhitaryan with ease in the 76th minute to set up Marcos Alonso for the winner.
Rudiger, Azpilicueta and Kante have also played a significant amount of time for the Blues in their past two games, which might restrict them to perform at their level best in the game which could decide their season ahead.