Darron Gibson is set to undergo surgery on his injured knee.
Gibson was stretchered off during the first half of the Republic of Ireland's 3-1 win over Kazakhstan on Tuesday evening.
A subsequent scan showed he has damaged his anterior cruciate ligament (ACL) and the midfielder will require an operation.
The length of time the 25-year-old will be best determined once the surgery is completed.
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 focussed on repairing the damaged ACL.