Jordan Henderson is an injury doubt for England's World Cup semi-final against Croatia with a tight hamstring, Sky Sports News understands.
It is understood the problem is not too serious, but England's medical staff will manage the Liverpool captain's fitness carefully ahead of Wednesday's match.
The squad resume training on Monday for the first time since Saturday's quarter-final win over Sweden at their Repino base after having a rest day on Sunday.
Jamie Vardy is another injury concern for England boss Gareth Southgate - he was unavailable for Saturday's 2-0 win after sustaining a groin strain in extra-time against Colombia last Tuesday.
Henderson has started all but one of England's games - the 1-0 defeat to Belgium when Southgate made eight changes to his starting XI in the final Group G match.
During England's last-16 match against Colombia, Henderson ran more than two kilometres further than any other player on the pitch.