Watford are on the brink of signing Younes Kaboul and Roberto Pereyra but it remains to be seen whether they will be available to face Chelsea.
Brice Dja Djedje and Isaac Success remain sidelined, while Ben Watson is suspended after being sent off 12 minutes after coming on at Southampton.
Chelsea have no fresh injury concerns and could be unchanged from the side that beat West Ham on Monday.
Mikel John Obi remains on international duty with Nigeria at the Olympic Games.
MOTD COMMENTATOR'S NOTES
Mark Scott: "When thoughts turned to the managerial duels this season that have a bit of added spice, this one might have slipped under the radar a little.