Reece James is out while Jorginho and Timo Werner are on the bench after late fitness tests ahead of the trip to Vicarage Road, after suffering blows in the 1-1 home draw with Manchester United.
N’Golo Kante, Mateo Kovacic and Ben Chilwell are absent, while Romelu Lukaku’s return from an ankle injury is carefully handled and the Belgian is still not back in the starting XI.
Saul Niguez is making a rare start after his loan transfer on Atletico Madrid deadline day, partnering with Ruben Loftus-Cheek.
Kai Havertz starts off after missing games against Juventus and United, with Christian Pulisic also named up front with Mason Mount completing the front row. There is also a place for Andreas Christensen in defense as Thiago Silva retires.
Chelsea XI: Mendy; Chalobah, Christensen, Rudiger; Azpilicueta, Loftus-Cheek, Saul, Alonso; Mont, Havertz, Pulisic.
Subscribers: Kepa, Sarr, Thiago, Jorginho, Barkley, Lukaku, Ziyech, Hudson-Odoi, Werner.