Despite being told that he has not broken his foot, as was previously feared, the Republic of Ireland international may still miss the game due to heavy bruising.
Everton physio Mick Rathbone said: "Lee has got a badly bruised foot. He went for a precautionary scan which was all clear but is doubtful for Wednesday's game with Chelsea. He's still feeling a little uncomfortable so we'll keep an eye on him over the next few days."