The Football Association have confirmed goalkeeping coach Ray Clemence has been admitted to hospital.
Clemence began to feel unwell on Friday, when he missed training and also Saturday's friendly win over world champions Spain.
"Ray Clemence has been unwell while with England and is having tests in hospital," said an FA statement.
Clemence, 63, won 61 England caps and is now serving under his fifth national team boss.
He will also be missing when England train this morning ahead of Tuesday's friendly with Sweden, when it is highly unlikely he will be back in the dug-out.
"At this time Ray would like to thank everyone for the kind messages he's received and the FA would like to request privacy for his family," the statement added.