The England midfielder, who has been with Everton since the age of 11, left the club’s Finch Farm training base with his leg in a brace after sustaining the injury on Friday and could be out for up to six weeks.
The youngster will not travel with the squad to the King Power Stadium and the nature of the 20-year-old’s injury should become clearer after he undergoes a scan.
Barkley – Everton’s Young Player of the Season last year – played in the club’s last three pre-season games and featured on 38 occasions last year, scoring three times.
Barkley, who signed a new long-term contract at Goodison Park earlier this month, could be replaced in Everton’s starting line-up this weekend by new signing Muhamed Besic.
Roberto Martinez’s side come up against Arsenal and Chelsea in their next two league games and Barkley appears to be facing a race to be fit for those games.