Everton manager Roberto Martinez has confirmed that captain Phil Jagielka could be out for up to eight or nine weeks after sustaining a knee injury in the defeat at Arsenal.
The England centre-back was forced off in the second half of Saturday's 2-1 defeat at the Emirates Stadium, and scans have shown that he has damaged a medial ligament.
"The medial ligament is affected and it's an injury that is quite straightforward," Martinez told Everton's official website.
"It's hard to tell [how long he will be sidelined for]. The medial ligament depends on what area there is damage to determine how quickly you can recover.
"At the moment we are going to make sure he gets the right course of treatment. I wouldn't expect anything longer than eight to nine weeks."
Jagielka has made 12 appearances for Everton this season.