Everton have confirmed speculation that their midfielder Darron Gibson damaged the anterior cruciate ligament in his right knee last night.
The 25-year-old sustained the problem during the Republic of Ireland's 3-1 victory over Kazakhstan last night.
Having had the injury assessed, the Toffees have revealed that the former Manchester United midfielder will shortly undergo an operation to correct the problem.
"The length of time the 25-year-old will be best determined once the surgery is completed," read a statement on the club's official website.
"However, the scans did confirm to Everton's medical team that no additional damage was sustained to the structure of the right knee, ensuring all treatment and rehabilitation will be focused on repairing the damaged ACL."
Gibson is not expected to play again this season.