The Brazilian must wait to make his debut for the champions while the Belgium international drops back to the bench
Chelsea have left new signings Alexandre Pato and Matt Miazga out of their squad to face Watford on Wednesday while Eden Hazard starts on the bench.
Guus Hiddink names the same team that beat Arsenal in the Premier League last weekend, meaning Hazard remains on the bench despite impressing in the FA Cup win over MK Dons.
Chelsea make four changes from their FA Cup side with Cesar Azpilicueta and Kurt Zouma replacing Baba Rahman and Gary Cahill, with Jon Obi Mikel and Willian come in for Ruben Loftus-Cheek and Hazard in midfield.
Watford, meanwhile, make two changes to their side with Jose Holebas replacing the ineligible Nathan Ake while Sebastian Prodl comes in for Miguel Britos. New signing Mario Suarez has been named on the bench.
Watford XI: Gomes; Paredes, Prodl, Cathcart, Holebas; Watson; Behrami, Capoue; Jurado; Deeney, Ighalo. Subs: Pantilimon, Nyom, Suarez, Amrabat, Guedioura, Anya, Abdi.
Chelsea XI: Courtois; Ivanovic, Zouma, Terry, Azpilicueta; Mikel, Matic; Willian, Fabregas, Oscar; Diego Costa. Subs: Begovic, Cahill, Baba Rahman, Loftus-Cheek, Kenedy, Traore, Hazard.
- Goal