Leicester City defender Callum Doyle has been ruled out for up to four months with an injury that the club are unable to fully identify.
The 19-year-old was hurt in their 1-0 win against Bristol City and has since undergone tests.
When asked if he knew what the injury was, the Foxes boss Enzo Maresca replied: "Not exactly to be honest".
Maresca went on to say the Manchester City loanee will miss "12 to 16 weeks" and will stay at Leicester to recover.
Before the Foxes' Carabao Cup defeat by Liverpool during the week, Maresca had already said Doyle would be out for "a long time".