TEAM NEWS
Marco Silva confirmed Everton are still without defenders Phil Jagielka and Leighton Baines in his pre-match press conference.
The Blues boss also admitted Yerry Mina is a doubt for the trip to Hertfordshire.
For the Hornets, influential midfielder Roberto Pereyra and striker Isaac Success (both hamstring) may again miss out but defender Kiko Fermenia (hamstring) will be assessed ahead of kick off.
Midfielder Abdoulaye Doucoure could also feature after shaking off a knee injury but Sebastien Prodl remains a long-term absentee.
FORM
Everton will be looking to replicate the performance if not the result from Wednesday night’s 2-0 defeat to Manchester City.