Everton midfielder Ross Barkley is facing six weeks out of action after suffering a knee injury in training, Goodison Park sources have told ESPN FC.
The England international left the club's Finch Farm training base with his leg in a brace after the incident on Friday.
Barkley, 20, is scheduled to undergo a scan to determine the seriousness of the injury and it means manager Roberto Martinez must revise his plans for Everton's opening Premier League fixture at Leicester on Saturday.
Liverpool-born Barkley, a product of Everton's youth set-up, committed his long-term future to the club in July by signing a four-year contract.
He established himself as a regular in the first-team at Goodison Park last season, making 34 Premier League appearances and scoring six goals.
Barkley's form earned him a place in England's squad for the World Cup finals in Brazil, where he came off the bench in the 2-1 defeats against Italy and Uruguay before starting the 0-0 draw against Costa Rica.
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