Everton suffered an injury blow towards the end of the their 2-1 defeat against Manchester United at Old Trafford yesterday, when young centre back John Stones was stretchered off with an ankle problem.
And according to BBC Sport manager Roberto Martinez says he expects to be without Stones for "the next few weeks".
"We will have to wait for the medical department to assess it but for him to come off the pitch early it is definitely something," he added.
It is also a problem for England manager Roy Hodgson, who has had to promote Arsenal defender Calum Chambers from the Under 21s for the Three Lions upcoming Euro qualifiers at home to San Marino and away to Estonia.
The Everton defender made his England debut in the 3-0 victory against Peru on 30 May and has received four caps so far. Centre back by trade, Stones has been filling in at right-back for his country, and started there in the 2-0 win in Switzerland last month.
Arsenal defender, Chambers, who made his full England debut against Norway in September, was originally called up to the Under 21 side for their crucial two-legged Euro 2015 play-off match with Croatia.
But he was always the back-up choice, should anyone withdraw from the senior side, and it appears now he will get his chance.
Hodgson had only named three recognised centre backs in his 21-man squad; John Stones as well as Everton team-mate Phil Jagielka and Chelsea's Gary Cahill.
But now 19-year-old Chambers, who has filled in at the heart of the Arsenal defence several times this season, will join the squad.
It is understood Chambers will still play for the Under 21s in their game at Wolves' Molineux on 10 October but be loaned to the senior team in case of a defensive emergency.
England's first game of their international double-header is against European minnows San Marino on 9 October followed by a trip to Estonia on 12 October.
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