Seamus Coleman could miss as many as four weeks after sustaining a calf injury in Everton's win over Manchester City on Wednesday night.
The Irish right-back pulled his calf muscle late in the Toffees' 2-1 Capital One Cup semi-final first leg victory at Goodison Park, ending the game on the bench after Roberto Martinez had used all three of his substitutions.
Coleman joined injured striker Romelu Lukaku and crocked midfielder Tom Cleverley on the bench and according to Martinez, will now be out of action for at least three weeks.
"Seamus is probably the most serious of the three," said the Spaniard.
"He has pulled his calf and that type of injury usually takes three or four weeks to fully recover."
Everton will now prepare for Saturday's FA Cup third round clash with Dagenham & Redbridge before again facing City in the Premier League next Wednesday.