Yannick Bolasie will undergo surgery after sustaining a serious knee ligament injury against Manchester United on Sunday.
Bolasie picked up the injury in the second half of the 1-1 draw at Goodison and was replaced by Enner Valencia.
Scans have now confirmed anterior cruciate ligament damage to the right knee. Bolasie will undergo surgery in the next few days.
He had played every game since arriving at the Blues from Crystal Palace in August.