Everton are assessing the extent of a hamstring problem for Seamus Coleman.
The Irish international was replaced by John Stones midway through the second half of Monday night's 1-1 draw with West Brom at the Hawthorns.
After the game, manager Roberto Martinez revealed the cause of the defender's enforced withdrawal.
He said: "Seamus felt his hamstring a little bit. We are going to assess him.
"We are going to be cautious and see what the problem is but it’s not a good sign because Seamus would never want to come off the football pitch.
"He has been in a terrific moment of form so we will try to get him back on as quick as we can."
Coleman has notched up 31 competitive games for club and country this season, netting six goals in the process - including an impressive haul of five in his last 11 outings for the Blues.