Dominic Calvert-Lewin has suffered a setback in his injury comeback bid.
Calvert-Lewin last featured for Everton in their win over Brighton at the end of August after playing through quadricep issues in addition to a broken toe.
Rafael Benitez confirmed last month that he expected the England striker to be missing for longer than the initial three-week diagnosis for his return.
However the Blues confirmed on Wednesday that Calvert-Lewin is now set to spend an extended spell out of action after a relapse during rehabilitation.
It is the second injury blow to befall Benitez’s side within the space of 24 hours, after midfielder Abdoulaye Doucoure was sidelined by a broken foot.
“Dominic Calvert-Lewin has suffered a setback in his rehabilitation from a quadriceps injury and will remain out for a number of weeks,” a club statement confirmed.
“The Everton striker has not played since the Blues’ Premier League clash at Brighton & Hove Albion on 28 August, when he scored from the penalty spot in a 2-0 victory.
“Calvert-Lewin will continue to receive specialist treatment and an update on the England international’s fitness will be provided in due course.”
Everton remain hopeful that Richarlison will complete the final stages of his return from a knee injury to feature against former club Watford on Saturday.