The pressure ramped up on Antonio Conte following last week's 3-0 home defeat by Bournemouth.
As expected, there is no Barkley in tonight's Chelsea squad and it will be interesting to hear what Conte has to say about his latest setback.
Chelsea TV say the Spaniard, who has yet to miss a Premier League game so far this season, is nursing a minor muscle injury...
No Marcos Alonso for Chelsea, who hand a recall to Victor Moses. Christensen and Barkley are replaced by Luiz and Willian as Conte continues to deploy a false nine.
Giroud and Emerson are both included as substitutes. Callum Hudson-Odoi keeps his spot on the bench, but Ethan Ampadu misses out.
Two changes from Watford, who switch to a back three, with Dutch duo Daryl Janmaat and Marvin Zeegelaar replacing the injured Christian Kabasele and Cleverley.
It appears that Ndong actually has completed his suspension as he joins fellow new signing Dodi Lukebakio and 18-year-old defender Joy Mukena on the bench.
New arrivals Olivier Giroud and Emerson Palmieri could both feature in Chelsea's squad tonight, while Brazilians David Luiz and Willian have returned to training after injury.
Andreas Christensen and Alvaro Morata remain sidelined and it was reported over the weekend that Ross Barkley had suffered another hamstring problem at Cobham, the severity of which is currently unknown.