Midfielders:
Kante
Sarri will play new Kante and new recruit Jorginho in the defensive midfield role.
Kante has been phenomenal for both Chelsea and France. He is often called the best defensive midfielder in the world, and is capable of making interceptions and even holding the ball for a long time.
Kante was the most influential player for Leicester City when they won the league in 2016.
Jorginho
Sarri has immense faith in Jorginho, who was with him at Napoli too. Jorginho was the main reason why Napoli finished second in the league; he played the most passes in the Serie A last season among Europe's top five leagues.
Matteo Kovacic / Cesc Fabregas
Matteo Kovacic was signed as a loanee on the last day of the transfer window, as part of the deal in which Courtois moved to Real Madrid.
Kovacic is the kind of player that suits Sarri's style of play. He can do both dribbling and passing, which will be crucial for Chelsea under Sarri
According to Squawka, Matteo Kovacic completed 115 take-ons at a success rate of 82.40% - mind-boggling numbers.
Fabregas can be the alternative when Kovacic is not able to play due to any reason. Fabregas is a Spanish footballer known for his passing skills. He can be a game-changer on his day.
Fabregas was included in the squad for the Community Shield, which indicates that he will form a key part of the manager's plans this season.
Sarri has a number of other options in midfield too such as Victor Moses, Drinkwater and Ross Barkley.